知识与资讯
翻译案例
 
【工程施工类翻译】洞身开挖
发布时间:2011-7-14 19:43:00||  点击:3489次||  文章分类:翻译案例||  发布人:翻译家(Fanyijia.com)


洞身开挖

一、 范围

本节工作内容包括洞身及车行横通道、人行横通道、辅助坑道的开挖以及竖井、钻孔爆破、施工支护、装渣运输等有关作业。

 

二、一般规定

1. 承包人应在开挖前28d根据地质、机械设备等条件向监理工程师提出符合隧道具体情况的施工方案(包括开挖顺序、爆破、施工照明、通风、排水、支护、出渣等),并经监理工程师审查批准。施工方法采用新奥法;根据施工中具体情况的变化,也可及时改变施工方法,但都必须报经监理工程师批准。

2. 承包人应根据批准的施工方案,采用现代化施工技术,合理地安排工序,科学地组织隧道施工,以保证合格的施工质量和合理的计划进度。

3. 承包人应安排好施工过程的测量,以保证隧道按设计方向和坡度施工,使开挖断面符合图纸所示尺寸,尽量做到不欠挖和不超挖。洞内还应每隔50m设置一个水准点。

4. 监理工程师批准的施工方法,如有导致工程缺陷或失败的情况,都不应减轻承包人在施工中的责任。

5. 在施工过程中,承包人应根据对开挖面的直接观察、围岩变形的量测结果。辅以超前地质预报,结合岩层构造、岩性及地下水情况,提出围岩分级的修改意见,并判定坑道围岩的稳定性,提出相应的处理措施,报请工程师批准。

 

三、 开挖作业

1. 开挖要求

(1)承包人应根据监理工程师批准的施工方案或其后批准的修改方案完成开挖作业。洞口处边坡防护工程未完成前,不得进行洞身开挖。

(2)为了最大限度地利用围岩自承能力,承包人必须采用减少围岩扰动的方法进行洞身开挖。各类围岩的开挖方法按设计并符合《公路隧道施工技术规范》(JTJ 042-94)的有关规定。

(3)洞身开挖断面尺寸应符合图纸要求,边沟、电缆沟及边墙基础也同时开挖,所有开挖应按图纸标明的开挖线进行施工,并一次挖够。在开挖过程中,承包人应随时测定隧道轴线位置和标高。预留洞室在施工前应与图纸进行核对,确保洞室的数量与位置正确。

(4)在开挖的进程中应考虑按有利于减少超挖、有利于围岩的稳定的施工方法进行。无论承包人出于何种原因所造成的超过允许范围的超挖以及这部分超挖的回填,所有材料和施工费用均由承包人负责。

(5)严格控制断面开挖,不应欠挖,仅在岩层完整、抗压强度大于30MPa,经监理工程师确认不影响衬砌结构的稳定和强度时,岩石个别突出部分(每平方米内不大于0.1m2)可侵入衬砌,侵入量不大于50mm。拱脚、墙脚以上1m内断面严禁欠挖。

(6)采用台阶法施工时,台阶不宜分层过多,上下台阶之间的距离尽可能满足机具正常作业,并减少翻渣工作量;当顶部围岩破碎,需支护紧跟时,可适当延长台阶长度。

(7)当两相对掘进工作面接近打通时,两端施工应加强联系,统一指挥。当两工作面的距离剩下15m时,应从一面掘进贯通。

(8)浅埋隧道开挖时应严格控制地表沉陷,减小循环开挖进尺和防止塌方。为此,应根据具体情况,采取适当措施,如:

a. 施工中为减少对围岩扰动,宜采用单臂掘进机或风镐开挖,爆破开挖时应遵循短进尺、强支护、弱爆破、勤观测的原则;

b. 应加强对拱脚的处理,安设拱脚锚杆;

c. 及时施作仰拱或临时仰拱;

d. 若初期支护变形过大,又不宜加固时,可对洞周2~3m范围内的围岩进行系统深孔岩石注浆;

e. 在V级或VI级软弱破碎围岩中施工或洞中有涌水时,应采用预注浆,或从地表安设地层锚杆,或洞内环形固结注浆或采用管棚法加固地层;

f. 应加强地表下沉、拱顶下沉的观测及反馈,以指导施工。

(9)隧道内两相向施工中线在贯通面上的极限误差应符合表-1的规定。由于贯通误差引起增加的工程量均不再另予计量和支付。

 

                                        隧道中线极限贯通误差                  表-1

类 别

两相向开挖洞口间长度(m)

两端施工中线在贯通面上的极限误差(mm)

横向

<3000

±150

3000~6000

±200

>6000

±300

高程

不限

±70

 

 

(10)由洞外设置洞口基点桩时,测量误差和洞内支导线放样测量误差引起的贯通面产生的中误差应不大于表-2的规定。

 

                                         贯通中误差                         表-2

测量部位

两开挖洞口间长度(m)

高程中误差(mm)

<3000

3000~6000

>6000

贯通中误差(mm)

洞 外

45

60

90

25

洞 内

60

80

120

25

全部隧道

75

100

150

35

 

 

(11)对洞口段软弱破碎岩层,稳定开挖工作面的常用措施有:环形开挖留核心;用喷射混凝土封闭开挖工作面;超前锚杆或超前小钢管;管棚;超前小导管注浆;临时仰拱封底;开挖工作面及围岩预注浆等。施工时应按图纸规定进行,如无规定,施工时视地质条件、地下水状况、施工方法等进行选择,报请监理工程师批准。

(12)隧道洞口软弱围岩段采用台阶法开挖时,上下台阶之间的距离不能大于30m,当洞口段位于松散堆积体内时,应采用微台阶法或环形开挖预留核心土法开挖,上下台阶之间的距离不能大于5m,仰拱和拱部钢架应及时全封闭,仰拱砼应及时浇筑,以避免沉降过大而侵入设计限界。

2. 钻爆设计

(1)在岩石隧道爆破作业的掘进中,对爆破技术诸要素如钻眼大小、孔深、间距、药量、钻眼分布与起爆顺序等应慎重研究与严格控制。

在进行钻爆施工前至少14d,承包人应完成钻爆设计并报请监理工程师批准。

(2)钻爆设计应在综合研究地质条件、开挖断面、开挖方法、掘进循环进尺、钻眼机具、爆破器材等的基础上进行。其主要内容有:炮孔布置图(包括掏槽方式、钻孔深度及斜度);装药结构图(包括装药量及炮孔堵塞方式);钻爆参数表;起爆方法和顺序,必要时应绘制爆破图;主要技术经济指标及必要的说明。

(3)钻爆设计应使用光面爆破或预裂爆破技术。爆破参数的选择,均应通过试验确定;无试验条件时,可参照《公路隧道施工技术规范》(JTJ 042-94)中的有关参数。

a. 光面爆破的要求

(a)残留炮孔痕迹,应在开挖轮廓面上均匀分布。炮孔痕迹保留率:硬岩不少于80%,中硬岩不少于70%,软岩不少于50%。

(b)相邻两孔之间的岩面平整,孔壁不应有明显的爆破裂隙。

(c)相邻两孔之间出现的台阶形误差不得大于150mm。

(d)钻孔偏斜误差不超过1°。

b. 预裂爆破的要求

(a)在主要爆破眼引爆前,瞬时爆破单排密距孔眼,可获得沿开挖线的预裂面,减少对主要爆破眼的爆破影响,从而减少外层岩石的破损。

(b)最理想的情况是单一的断裂应连接到邻近的爆破眼,并在每个预裂孔眼内还保留一半的孔。

(c)预裂爆破孔的预裂缝宽度一般不宜小于5mm。

(d)钻孔偏斜误差不超过1°。

3. 钻爆作业

(1)钻爆作业必须按照钻爆设计进行。当开挖条件出现变化时,爆破技术应随围岩条件的变化而作相应改变。

(2)钻炮眼前应绘出开挖断面的中线、水平和断面轮廓,并根据爆破设计标出炮眼的位置,经检查符合设计要求后,方可钻眼。

(3)炮眼的深度、角度、间距应按设计要求确定,并应符合设计精度要求。

(4)钻眼完毕,应按炮眼布置图进行检查,并做好记录,经检查合格后,方可装药。

(5)装药前应将炮眼内泥浆、存水及石粉吹洗干净,所有装药的炮眼均应及时堵塞炮泥,周边眼的堵塞长度不宜小于200mm。

采用预裂爆破法时,应从药包顶端起堵塞,不得只在眼口堵塞。

(6)采用电力起爆时,应按《土方与爆破工程施工及验收规范》(GB J201-1983)及《公路隧道施工技术规范》(JTJ042-94)的有关规定执行。

(7)周边眼以一次同时起爆为宜。当在软岩地段必须对爆破震动加以控制时,周边眼可根据地质条件分组起爆。或加密周边孔眼,采取小孔眼、低装药量的方法。

(8)爆破后应设专人负责清顶,同时要对开挖面和未衬砌地段进行检查,如察觉可能产生险情时,承包人应采取措施,及时处理。

(9)双连拱衬砌断面的开挖爆破属分部开挖作业,应严格遵守“短进尺、弱爆破”的原则,遵守有关“爆破与震动”的作业要求;核心围岩的开挖爆破,不得对已衬砌结构的安全产生影响。

4. 雷电期间作业

(1)雷电将临时,应立即停止所有地面或地下的炸药运输和短程搬运,人员应立即撤至安全地点,并将雷电来临或雷电已过的信号,通知洞内工作人员。

(2)爆破作业已完成的地段,承包人应提供、安装并使用经批准的雷电监控器和自动报警灯。

5. 爆破与震动

(1)爆破或其它作业所引起地面震动,不得损坏地面现有各项设施。

(2)承包人应提供合格的仪器、量测人员和资料分析人员,监测并记录每次爆破的震动情况及空气增压情况,调整爆破作业,使震速不超过允许值,并防止开挖失稳。

(3)所有的爆破和施工操作,对地面现有建筑物震动的最大震速应小于25mm/s。

对于新浇筑混凝土的震速要求,不得超过表-3规定值。

 

                                        新浇筑混凝土的震速限值                   表-3

混凝土龄期(h)

震速限值(mm/s)

混凝土龄期(h)

震速限值(mm/s)

12~24

6.25

48~120

25

24~48

12.5

 

 

(4)在最邻近爆破地点的现有建筑物所量测的爆破冲击噪声,不得超过130dB;使用有线频反应的最大冲击记录仪记录的爆破时空气超压不得超过0.005MPa。所有涉及到监控的仪器、设备都必须由承包人自备,并根据相关要求使用。

(5)合同图纸中规定禁止爆破的地方严禁爆破。有关震动记录资料应随时提供监理工程师检查,必要时应提供复印件。

6. 爆破安全措施

(1)隧道爆破作业,以及爆破器材的管理、加工、运输、检验和销毁等工作必须遵守《爆破安全规程》(GB6722-2003)的有关规定。

(2)爆破器材的领取和使用,必须做好原始记录,并做好记录资料的归档工作。

(3)进行爆破时,人员应撤至受爆破影响范围之外,一般距爆破工作面的距离不小于200m。爆破期间,除引爆电路外,所有动力及照明电路均应断开或改移到距爆破点不小于50m的地点。

(4)当开挖面与衬砌面平行作业时,应根据混凝土强度、围岩特性以及爆破规模等因素确定其距离,一般不宜小于30m。

(5)瓦斯隧道必须采取电力起爆,使用安全炸药及毫秒电雷管,不得采用导火索起爆,不得使用裸露药包。

(6)瓦斯隧道装药爆破前必须进行安全检查,确保瓦斯浓度小于1%。

(7)爆破后,经通风吹散炮烟,检查确认掌子面空气合格、等待时间超过15min后,方准许工作人员进入爆破区域作业。

7. 有害气体安全措施

(1)坑道中如遇有害气体,所有人员应立即停止工作,并撤至洞外。承包人应采取措施排除有害气体,在确认无危险后,方可继续进洞施工。

(2)承包人应对有害气体进行定时检测、记录。配置自动检测、纪录仪器、设备,并报监理工程师检查,隧道中有害气体不得超过第507.03-1(2)款的标准。

(3)在有有害气体的隧道中施工时,应安装连续监测可燃气体和有害气体的分析仪和报警器。报警器既能视觉报警,又能听觉报警。

(4)承包人应为工作人员提供各种必要的安全工具、安全灯,在可能出现有害气体地区还应提供防毒面具、氧气补给设备等。

 

 

TUNNEL EXCAVATION

I.  SCOPE

The works of this section include excavating of tunnel body, carriage gallery, pedestrian gallery, auxiliary gallery and the related works such as shaft construction, drilling and blasting, tunnel supporting, excavated material loading and hauling etc..

 

II. GENERAL REQUIREMENTS

1. The Contractor shall submit construction program (including excavation sequences, explosion, construction lighting, ventilation, drainage, support, ballast removal, lining, etc.) that is most suitable to the actual conditions of the tunnel, according to such conditions as geology, mechanical equipment to the Engineer for review and approval 28 days before excavation. The New Austrian Tunneling Method is advisable to be applied. Timely change may be also made for the construction method based on the actual conditions and must be approved by the Engineer to match with changes of specific conditions.

2. The Contractor shall adopt modernization construction technique and reasonably arrange procedures, organize scientifically construction according to the approved construction program to ensure qualified project quality and reasonable schedule.

3. The Contractor shall arrange correctly measurements during construction to ensure that the tunnel is constructed according to design direction and slope gradient and excavated section conforms to dimensions shown on the Drawing. Excavated dimensions are done correctly. Benchmark is located at each 50m inside tunnel.

4. The Contractor shall not be relieved of his responsibility in defects or failure of tunnel works due to the construction method approved by the Engineer.

5. During construction, according to the direct observation to cutting face, the mseasurement to deformation of the surrounding rock, with assistant of advanced geological prediction and supplement of strata formation, lithological characters and groundwater, the Contractor shall raise his modification opinion for classification of surrounding rock, judge stability of the surrounding rock around the gallery, put forward corresponding treatment and submit to the Engineer for approval.

 

III. EXCAVATION OPERATION

1. Excavation Requirements

(1) The Contractor shall, in accordance with the approved construction methods or the succeeding approved modification plans, complete the excavation operation. Before the completion of the protection work of side slope at the tunnel opening, the tunnel body excavation shall not be started.

(2) The Contractor shall adopt the excavation method that reduces disturbance on the surrounding rock in tunnel body in order to utilize the self-supporting characteristics of the surrounding rock to the maximum limitation. For methods of excavation of different surrounding rock, stipulations in Technical Specifications for Construction of Highway Tunnel (JTJ 042-94) shall be referred to.

(3) During excavation of tunnel body, all cross section dimensions shall conform to the requirements on the Drawings. Side ditch, cable trench and foundation of sidewall shall be excavated simultaneously. All the excavation shall be carried out according to the excavation line shown on the Drawings, and shall be completed in one excavation. In the course of excavation, the Contractor shall from time to time survey the position of tunnel axis and elevation. Before construction of tunnels chambers for provision, they shall be checked against the Drawings to ensure the quantity and accurate position of them.

(4) During excavation, the Contractor shall use methods, which are beneficial to the reduction of over-excavation and the stability of the surrounding rock. The cost of all materials and construction for the overreach beyond the allowed range made by the Contractor for whatever cause including backfill of over-excavation are the Contractor's liability.

(5) Under-excavation shall not occur in excavation of tunnel except when rock stratum is perfect with compressive strength more than 30MPa, and the Engineer confirms that the under-excavation will not affect the structural stability and strength of the linings, in this case, individual part of a rock (not greater than 0.1 m2 per square meter) may intrude into the lining within 50mm. Under-excavation on the cross section less than l m above footings of the arch and the wall is strictly forbidden.

(6) When using bench cut method in tunnel construction, the bench is preferable not to be divided into too many steps, the distance of lower part and the upper part of the bench shall satisfy as far as possible the normal operation requirements of the machines/tools and the re-handling of ballast shall be reduced to the minimum. provided the top surrounding rocks are broken and following up support is required, the bench may be properly lengthened.

(7) When the working faces of opposite sides are nearly excavated through, the construction of both sides shall contact with each other tightly. When the distance of two working faces remains 15m, the tunnel shall be excavated through from one side.

(8) In excavation of shallow buried tunnel, it should be carry out to decrease the footage to prevent collapse, which shall benefit to diminish the settlement of ground surface. So, according to actual conditions, the proper measures are taken as follow:

a. Single arm tunneling machine or pneumatic pick is used so as to decrease the disturbance of surrounding rock in construction. The principle of short footage, strong support, weak blasting, regular observation and surveying shall be observed for blasting excavation;

b. Strengthen the treatment of springing, and set anchor bar of springing;

c. Construct inverted arch or temporary inverted arch in time;

d. Make deep hole rock grouting for the surrounding rock 2~3m around the periphery of tunnel when deformation of the primary support is too large and reinforcement is not appropriate..

e. When constructing in weak and broken surrounding rock of Class Ⅳor ClassⅤ, or there is water emerging in the tunnel, such measures shall be adopted as pre-grouting, or setting stratum anchor bar from the ground surface, or ring consolidation grouting in the tunnel or strengthening the stratum by using pipe-shed.

f. Observation and feedback of settlement of ground surface and settlement of arch crown shall be strengthened so as to instruct construction.

(9) Ultimate deviation of two constructional centerlines in opposite directions on the through face of tunnel shall conform to stipulations in Table-1. The additional works caused by through error shall not be measured and paid separately.

 

Table -l Ultimate Through Error of Tunnel Centerline

Kinds

Length between 2 opposite excavated tunnel fronts (m)

Ultimate deviation on the through face of constructional centerlines for the two ends of tunnel (mm)

Transversal

<3000

±150

3000~6000

±200

>6000

±300

Elevation

No limit

±70

(10) When the bench mark of tunnel portal is located outside tunnel, measurement deviation and root mean square deviation on the through face caused by laying out route shall conform to stipulations in Table-2.

 

Table-2 Root Mean Square Error on the Through Face

Measurement location

Length between 2 opposite excavated tunnel fronts (m)

Mean square deviation of height(mm)

<3000

3000~6000

>6000

Root mean square deviation on the through face(mm)

Outside tunnel

45

60

90

25

Inside tunnel

60

80

120

25

All tunnel

75

100

150

35

 

(11) For soft and weak broken rock at tunnel opening section, usual measures are taken to stabilize excavated work face as follows: provided core part during circular excavation; excavation operation surface sealed by shotcrete; advance anchor bolt or advance tubule; pipe-shed; Advance tubule grouting; temporarily inverted arch subseal, pre-caste grouting of excavation operation surface and surrounding rock etc. Construction is carried out according to requirements of Drawing, if unspecified, the measures shall be selected according to geologic condition, ground water state and construction method during construction, this should be submitted to the Engineer for approval.

(12) When soft and weak surrounding rock at tunnel opening is excavated using bench cut method in tunnel construction, the distance of lower part and the upper part of the bench shall be less than 30m; when tunnel opening section is located in the bulk congeries, excavation is done using micro-benching tunneling method and circular cut provided core part soil method, the distance of lower part and the upper part of the bench shall be less than 5m; inverted arch and arch steel frame shall sealed timely, inverted arch concrete shall be grouted in time to avoid excessive settlement and intruding into design limited range.

2. Blasting Design

(1) In the blasting excavation in rock tunnel, key factors of blast technology, such as the size and depth of drill-hole, the interval between holes, the quantity of dynamite, the distribution of drill-hole, and the sequence of blasting, shall be studies carefully and strictly controlled.

At least 14 days prior to blasting construction operation, the Contractor shall complete the design of drilling and blasting, and submit it to the Engineer for approval.

(2) The design shall be carried out based on the comprehensive study of geological conditions, excavated section, method of excavation, excavation cycle footage, machines/tools of drilling, blasting materials, etc. The main contents are: layout of blast holes (including hole cutting type, drilling depth and obliquity); structural diagram of dynamite filling (including amount of dynamite and blast hole stemming method); parameter table of drilling and blasting; blasting method and sequence, blasting diagram (shall be drawn if necessary), and main technical and economic indices and necessary descriptions.

(3) Smooth blasting or pre-splitting blasting shall be used in drilling and blasting design. Blasting parameters shall be selected and determined through tests. If test conditions are not available, relevant parameter in Technical Specifications for Construction of Highway Tunnel (JTJ 042-94) may be referred.

a. Technical requirements for smooth blasting:

(a) Residual traces of blast holes shall be evenly distributed on the excavation contour surface. Retaining rate of blast hole trace: not less than 80% for hard rock, not less than 70% for median hard rock, not less than 50% for soft rock.

(b) Rock surface between two neighboring holes shall be flat and even, no evident blast fissures are allowed on the hole wall.

(c) Bench type deviation that appears between two neighboring holes shall not be greater than 150mm.

(d) The biased error of borehole shall not exceed 1°.

b. Requirements to the pre-splitting blast

(a) Prior to igniting the main blast hole, instantaneous blast in single-row and close rim hole may be used to obtain the pre-splitting Surface along excavation contour line which shall reduce the damage of outer layer of rock resulting from the main blast hole.

(b) The most ideal condition is that a single break line shall connect nearby blast hole one by one, and half blasting trace of the rim hole section is maintained in surrounding rock after blasting.

(c) The pre-splitting seam width of the pre-splitting blast hole is advisable to be not less than 5mm in general.

(d) The biased error of borehole shall not exceed 1°.

3. Drilling and Blasting Operation

(1) Drilling and blast operation shall be carried out according to its design. When the excavation condition changes, corresponding changes of blasting technology shall be made according to the variation of the condition of surrounding rock.

(2) Prior to drilling holes, the centerline and the level of excavated section, the outline of the section shall be drawn and the location of blast holes shall be marked in accordance with the blast design. When it conforms to the design requirements through checking, the drilling of holes may be started.

(3) Depth, angle and interval of blast holes shall be determined in accordance with design requirements and shall confirm to the requirements of design accuracy.

(4) When all holes have been drilled, check shall be carried out in accordance with the arrangement drawing of the blast holes, and records shall be taken. When qualification is proved through inspection, dynamite filling may be started.

(5) Mud, accumulated water, and rock powder in blast holes shall be blown out and washed clearly prior to filling the dynamite. All blast holes shall be blocked up timely with stemming. The blocked length of rim holes shall not be less than 200mm.

When the pre-splitting blast method is used, blocking up shall be made from the top of dynamite package but not from the mouth of the holes only.

(6) When electricity is adopted for ignition, the operation shall be carried out according to stipulations in Construction and Acceptance Specification for Earthwork and Blast Work (GBJ201-1983) and Technical Specifications for Construction of Highway Tunnel (JTJ 042-94).

(7) Rim holes are available to be detonated at the same time. They may be detonated in groups according to the geological condition, and blast shocking has to be controlled when operated in soft rock section. Or the rim holes are densified to detonated in small diameter hole and less explosive. 

(8) After blasting, exclusive person shall be assigned to clear the top and the surrounding, meanwhile inspecting the working face and un-lining section shall be carried out. If it is discovered that danger may occur, the Contractor shall take measures in time for eliminating.

(9) The excavation and blasting for continuous arch tunnel shall carry strictly out the principle of Short Footage, Weak Blasting and operation requirements of Blasting and Vibration. Excavation and blasting of nucleus rock in work face shouldn’t affect and even damage construction safety of lined structures.

4. Operation in Thundering and Lightning Period

(1) When thunder and lightning are approaching, all the ground or underground transport of dynamites and short distance hauling shall be suspended immediately; all personnel shall be evacuated to the safe places. The working personnel inside the tunnel shall be informed of the coming and passing over of the thunder and lighting by signals.

(2) In sections where the blast work has been finished, the Contractor shall provide, install and use approved thunder and lightning monitor apparatus and automatic alarm devices.

5. Blasting and Vibration

(l) The ground vibration caused by blasting or other operations are not allowed to damage existing building and public facilities.

(2) The Contractor shall provide qualified instruments, and assign measuring personnel and document analysis personnel, monitor and record every vibration situation of blasting and situation of air-pressure boost, adjust the blasting operation to make the vibration not exceed allowable value to prevent excavation instability.

(3) All blasting and construction operations shall guarantee the maximum velocity of vibration to existing building not exceed 25mm/s.

For new cast concrete, the vibration velocity allowed shall not exceed the stipulated values in Table-3:

 

               Table-3    The Vibration Velocity Limited Value of New Cast Concrete

Age of Concrete (h)

Limit of Vibration Velocity (mm/s)

12~24

6.25

24~48

12.5

48~120

25

(4) The blast shock associated noise measured in the existing building near the blast point shall not exceed 130dB. In recording the situation of blast with maximum shock recorder by wire frequency reaction, the extra-pressure of air must not exceed 0.005Mpa. All the instruments and equipment related to the monitoring shall be provided by the Contractor and used according to the relevant requirements.

(5) Blasting is be strictly forbidden in the non-blasting area regulated in the Contract Drawings. The related data of vibration record shall be submitted at any Time to the Enginneer for inspection, and duplicated copy shall be provided when necessary.

6. Safety Measures of Blasting

(l) Various works like managing, processing, transporting, inspecting and destroying of blasting materials, shall conform to relevant stipulations in Safety Regulations for Blasting (GB6722-2003).

(2) The original records for receiving and using of blasting materials shall be well done and well filed.

(3) During blasting, all personnel shall withdraw to areas outside the effective range, where normally shall be far away for the blasting site with a distance not less than 200m. In period of blasting, besides electric circuits for ignition, all other power or light circuits shall be switched off or move to places not less than 50m away from the blasting point.

(4) If the excavation work and lining work are to be taking place in parallel, a distance, which is usually not less than 30m, shall be kept according to the strength of concrete, surrounding rock character and the scale of blasting.

(5) In gas tunnel, electric firing, permissible explosive and millisecond detonator must be adopted, while fuse and exposed cartridge are prohibited.

(6) Before charging and blasting in gas tunnel, safety inspection must be done to ensure the gas density less than 1%.

(7) After blasting, the Constructors shall not allowed personnel to enter the blasting area until the smoke is blown over by fresh air, air in the work face is checked to be qualified and all personnel shall wait more than15min.

7. Safety Measures for Harmful Gas

(l) If harmful gas is existed in the tunnel, all the personnel shall stop work immediately and withdraw to the outside of tunnel. The Contractor shall take treatment measures, operation may not be continued in the tunnel until it is confirmed that there are no longer any danger.

(2) The Contractor shall make regularly inspection and record of the harmful gas with automatic detection and recording instrument/equipment provided. The recording data shall be submitted to the Engineer for checking. Harmful gas in the tunnel must not exceed the standard prescribed in Sub-clause 507.03-1(2).

(3) For construction in tunnels with harmful gas, alarm and analytical instrument for continuous monitoring of combustible gas and harmful gas shall be installed. The alarm is able to visually alarm and also auditory alarm.

(4) The Contractor shall provide his personnel with various necessary safety tools or instrument, safety lamp, gas mask and oxygen supplying equipment in the area where harmful gas is possible to appear.



  更多文章