共查询到20条相似文献，搜索用时 78 毫秒
1.
并设小净距隧道爆破振动响应分析及控爆措施研究 总被引：3，自引：0，他引：3
通过大量二维、三维数值模拟计算,分析了围岩、净距、埋深等条件对小净距隧道爆破振动特性的影响,研究了先行隧道不同支护体系、不同中岩墙加固措施及后行隧道不同施工方案等情况下,小净距隧道中后行隧道爆破开挖对先行隧道的影响。根据研究结果,提出了中岩墙加固宜采用注浆加固、先行隧道初期支护宜及时跟进并封闭、掏槽眼宜远离中岩墙以及开挖进尺不宜大于净距的1/3等小净距隧道爆破施工的控爆措施,以供小净距隧道爆破开挖设计、施工借鉴。 相似文献
2.
A Top Pilot Tunnel Preconditioning Method for the Prevention of Extremely Intense Rockbursts in Deep Tunnels Excavated by TBMs 总被引：2，自引：0，他引：2
Chuanqing Zhang Xiating Feng Hui Zhou Shili Qiu Wenping Wu 《Rock Mechanics and Rock Engineering》2012,45(3):289-309
The headrace tunnels at the Jinping II Hydropower Station cross the Jinping Mountain with a maximum overburden depth of 2,525 m,
where 80% of the strata along the tunnels consist of marble. A number of extremely intense rockbursts occurred during the
excavation of the auxiliary tunnels and the drainage tunnel. In particular, a tunnel boring machine (TBM) was destroyed by
an extremely intense rockburst in a 7.2-m-diameter drainage tunnel. Two of the four subsequent 12.4-m-diameter headrace tunnels
will be excavated with larger size TBMs, where a high risk of extremely intense rockbursts exists. Herein, a top pilot tunnel
preconditioning method is proposed to minimize this risk, in which a drilling and blasting method is first recommended for
the top pilot tunnel excavation and support, and then the TBM excavation of the main tunnel is conducted. In order to evaluate
the mechanical effectiveness of this method, numerical simulation analyses using the failure approaching index, energy release
rate, and excess shear stress indices are carried out. Its construction feasibility is discussed as well. Moreover, a microseismic
monitoring technique is used in the experimental tunnel section for the real-time monitoring of the microseismic activities
of the rock mass in TBM excavation and for assessing the effect of the top pilot tunnel excavation in reducing the risk of
rockbursts. This method is applied to two tunnel sections prone to extremely intense rockbursts and leads to a reduction in
the risk of rockbursts in TBM excavation. 相似文献
3.
V. M. S. R. Murthy Kaushik Dey 《Fragblast: International Journal for Blasting and Fragmentation》2003,7(3):149-166
Tunnels are required to be constructed for meeting different human needs such as power generation, transportation, underground storage, sewage etc. The predominant method of excavation, world over, is drilling and blasting owing to its capability to meet changing geo-technical conditions. Irrespective of the purpose for which the tunnels are driven, all are plagued by overbreak problems. Tunnels driven for water conveyance in hydroelectric power projects, in particular, need to be excavated with minimum overbreak to minimise cost of permanent concrete lining. Thus, predicting overbreak assumes significant importance to design site-specific blasts for minimizing rock damage. This paper presents a brief review of existing PPV (Peak Particle Velocity) based blast-induced rock damage estimation criteria and attempts to outline the ground vibration threshold levels for overbreak/rock damage in a tunnel driven through compact basalt. Rock damage manifested as overbreak is measured and correlated with the possible threshold levels of PPV. Also, the PPV levels for crack initiation and widening are proposed. The case pertains to a lake tap horizontal tunnel of Koyna Hydro-electric Power Project, India which is a water feeder tunnel for a fully underground hydroelectric power project. The tunnel was driven under a shallow rock cover of average depth ranging from 20 to 25m beneath a fully charged water body. The parting rock is mainly compact basalt. Blasting was carried out in two rounds in a controlled manner, i.e., by limiting the maximum charge per delay based on ground vibration monitoring. Ground vibration generated with free face (in second round) has been modeled and a new ground vibration propagation equation is proposed for tunnel blasting including the effect of an extra free face. The threshold limits of PPV for different degrees of overbreak/rock damage are proposed from extrapolated vibration predictor equation. The actual overbreak in the tunnel, measured using a Planimeter, varied from 2.45 per cent to 17.75 per cent of the finished tunnel area. The predicted overbreak from extrapolated PPV measurements is compared against the measured overbreak to validate the proposed blast-induced rock damage (BIRD) assessment model. The PPV level for overbreak was found to exceed 2050 mm/s in compact basalt. A linear relationship between the overbreak and maximum charge per delay is also established to design a tunnel blast in similar formations. 相似文献
4.
路堑边坡开挖对邻近既有隧道影响研究 总被引：5，自引：2，他引：3
设计中的承德迎宾大道路堑边坡邻近既有京承铁路21号隧道,边坡开挖后会对既有隧道产生不利影响。根据现场试验取得的围岩及隧道衬砌的力学参数,对边坡开挖进行了静力学和动力学数值分析,研究了路堑边坡可开挖的最大范围及爆破振动对隧道的影响。结果表明：当路堑二级边坡坡脚距离隧道中心线距离大于等于30 m时,边坡开挖后隧道衬砌内力虽有增加,但仍可保证结构安全。进行边坡爆破开挖时,如考虑3倍的安全系数,当京承铁路21号隧道衬砌振速小于1.5 cm/s时,隧道衬砌内产生的动拉应力小于衬砌极限抗拉强度,可按此控制指标进行现场监测。 相似文献
5.
Numerical Analyses of the Influence of Blast-Induced Damaged Rock Around Shallow Tunnels in Brittle Rock 总被引：2，自引：1，他引：1
Most of the railway tunnels in Sweden are shallow-seated (<20 m of rock cover) and are located in hard brittle rock masses.
The majority of these tunnels are excavated by drilling and blasting, which, consequently, result in the development of a
blast-induced damaged zone around the tunnel boundary. Theoretically, the presence of this zone, with its reduced strength
and stiffness, will affect the overall performance of the tunnel, as well as its construction and maintenance. The Swedish
Railroad Administration, therefore, uses a set of guidelines based on peak particle velocity models and perimeter blasting
to regulate the extent of damage due to blasting. However, the real effects of the damage caused by blasting around a shallow
tunnel and their criticality to the overall performance of the tunnel are yet to be quantified and, therefore, remain the
subject of research and investigation. This paper presents a numerical parametric study of blast-induced damage in rock. By
varying the strength and stiffness of the blast-induced damaged zone and other relevant parameters, the near-field rock mass
response was evaluated in terms of the effects on induced boundary stresses and ground deformation. The continuum method of
numerical analysis was used. The input parameters, particularly those relating to strength and stiffness, were estimated using
a systematic approach related to the fact that, at shallow depths, the stress and geologic conditions may be highly anisotropic.
Due to the lack of data on the post-failure characteristics of the rock mass, the traditional Mohr–Coulomb yield criterion
was assumed and used. The results clearly indicate that, as expected, the presence of the blast-induced damage zone does affect
the behaviour of the boundary stresses and ground deformation. Potential failure types occurring around the tunnel boundary
and their mechanisms have also been identified. 相似文献
6.
深埋洞室爆破开挖过程中围岩初始地应力的瞬态卸荷会诱发振动。针对圆形隧洞开挖,分析了地应力瞬态卸荷过程中围岩应变能、动能、径向应力做功3者之间的平衡机制,并采用量纲分析,建立了基于开挖岩体应变能的瞬态卸荷诱发振动衰减公式。结合锦屏二级引水隧洞和瀑布沟地下主厂房爆破开挖实例,开展了瞬态卸荷诱发振动的识别分离,并分析了诱发振动的衰减规律。研究表明：地应力瞬态卸荷诱发振动的峰值与被开挖岩体应变能密度的二次方根成正比,且开挖卸荷体积越大,诱发振动越强烈;与Lu-Hustrulid衰减公式相比,新衰减公式应用范围更广,使用精度更高。 相似文献
7.
Modeling and monitoring in a soft argillaceous shale tunnel 总被引：1，自引：1，他引：0
Taking advantage of measurements from an in situ monitoring program and an elastoplastic model using the finite-difference
method, this paper simulates and evaluates the deformation and stability of a tunnel in soft argillaceous shale. The elastoplastic
model is implemented in FLAC3D program to simulate the deformation and the stress of the soft argillaceous shale during construction.
In situ tests performed in the soft argillaceous shale tunnel show that the results from numerical simulations are in good
quantitative agreement with the measured in situ data. Results of the simulations also suggest that deformation rate is high
during the initial phase of tunnel excavation, compared with the later phase, but the time to reach a steady state remains
long. Entire primary support has been undergoing plastic deformation before construction of the secondary lining, which takes
the form of so-called “shear yield” from the middle to the bottom of the arch. Some auxiliary measures, especially the anchor,
should be applied to enhance stabilization because of the large compressive stress located at the arch springing of the tunnel.
The methodology applied in this article can be used to investigate the effect of construction on the performance of tunnels
in soft argillaceous shale. 相似文献
8.
Zheng Yang Wu Ke Sun Jie Chen Rong Li Yameng Yang Shifeng 《Geotechnical and Geological Engineering》2021,39(7):4765-4780
In the construction of the tunnel passing through the existing structure at an ultra-close distance, the existing structure will produce obvious deformation. It is very important to understand the deformation characteristics of the existing upper structure at different positions, especially to ensure the safety of the upper structure and improve the effectiveness of tunnel construction. In this study, the double-line tunnels of Qingdao Metro Line 4 passing under the Cuobuling station were taken as the engineering background, and a detailed 3D numerical model was established. This study comprehensively considered the on-site construction process, including grouting hardening, stress release of the excavated rock mass, grouting pressure and so on. The influence of tunnel excavation on the ground settlement was compared with or without a station structure, and the result was fitted with an empirical formula. Finally, the deformation of the station structure due to the excavation of the double-line tunnels was analyzed. The results of the analysis were as follows: (1) In the presence of the station structure, the excavation of the tunnels had a significant impact on the surface settlement. (2) The settlement of the sidewall caused by the excavation of the left-line tunnel was greater than that of the right-line tunnel, and the settlement at the junction of the sidewall and the bottom plate was smaller than that at other positions of the sidewall. (3) Compared with the roof and middle slabs, the floor of the station was more susceptible to the influence of tunnel excavation. Overall, the research could provide guidance and reference for similar double-line tunnels through existing stations.
相似文献9.
超小净距隧道爆破振动现场监测及动力响应分析研究 总被引：1，自引：0，他引：1
以南京地铁超小净距隧道为工程背景,结合国内外现有研究成果和规范,研究确保小净距先行隧道安全稳定的后行隧道爆破施工控制技术。以现代信息化施工理论为依据,充分运用现场监控量测,对先行隧道爆破质点振动速度进行监测分析和施工中爆破采用减振和隔振两方面控制技术;最终现场监测结果表明,优化后的循环进尺、段最大装药量与分段爆破差等爆破参数设计合理,该爆破设计在施工中未对先行隧道安全产生较大影响;同时,通过三维数值模拟计算,得到先行隧道壁面的质点振动速度随时间的变化规律,所得最大振速符合规范要求,也再次验证了优化后的爆破设计是合理的。通过数据分析得出隧道边墙的切向和径向振速比拱脚相应振速大,爆破面前方先行洞衬砌受爆破振动的影响稍大于后方衬砌,临近爆破点的左线隧道衬砌表面振动大于远离爆破点的衬砌表面振动。该研究成果为本工程施工提供了科学依据与技术指导,也可为类似隧道工程的爆破掘进工程在理论和施工方法上提供参考借鉴。 相似文献
10.
隧道原位扩建对邻近建筑物影响评估的研究 总被引：1，自引：0，他引：1
以重庆机场路渝洲隧道原位车道扩建为8车道工程为背景,通过文献调研、数值分析、监控量测和爆破监测等手段,对隧道原位扩建形式比选、扩建开挖对邻近建筑物变形影响和扩建爆破作业对邻近建构筑物影响等开展研究, 得到如下结论：（1）隧道原位扩建有单侧扩建、两侧扩建和周围扩建3 种形式,从施工力学分析,单侧扩建形式最优;（2）渝州隧道地表最大沉降曲线与小净距隧道类似;（3）地表沉降槽曲线的影响半径为40 m左右;（4）渝州隧道最大地表沉降差距离中线约10 m和30 m,实测临近建筑物沉降满足规范,建筑物安全;（5）爆破振动监测显示临近隧道和建筑物的振速值均远低于规范限制值,说明既有隧道形成的临空面对于吸收和释放爆破振动能量的作用很大。该研究成果为今后类似隧道原位扩建工程的施工方案提供参考借鉴。 相似文献
11.
Summary The excavation of underground tunnels close to existing substructures or the ground surface presents problems especially when blasting is being carried out. The high intensity waves which are generated and propagated through the rock medium, due to the detonation of explosives, may still have large amplitudes when they reach the ground surface. In order to study the vibration effects due to these propagating waves associated with blasting, a finite element simulation of tunnel blasting has been carried out in this paper.An example of a new tunnel excavated below an existing tunnel has been studied. Even though this problem is three dimensional in nature, due to the large computational efforts involved in three dimensional dynamic analysis, a two dimensional finite element analysis has been adopted. A pseudo-plane strain concept has been used since it has been found that the results obtained using such an approach are more realistic than the conventional plane strain analysis.It is concluded that results from such a numerical analysis could compliment the field investigations to produce guidelines for safe and controlled blasting. 相似文献
12.
Tunnel excavation produces stress changes to the ground and strain to the support lining, leading to the closure (convergence) or instability of the excavated area. Convergence recorded after section excavation is assigned to: (i) strain resulting from the progressive tunnel front advance (face advance effect) and (ii) the time-dependent properties of the soil material (ground creep effect). In the present study, based on the geodetic monitoring records of two recent road tunnels in Greece, a simple methodology to estimate the contribution of each of the two effects is presented. Our analysis reveals that at least half of the total deformation of the examined tunnel sections is due to ground creep, indicating that the major portion of tunnel deformation is due to the time-dependent properties of the ground; a result supported by previous studies from other tunnels as well. 相似文献
13.
14.
考虑累积损伤效应的围岩变形特性研究 总被引：1，自引：0，他引：1
隧道爆破开挖诱发的动力扰动作用范围往往远大于其开挖进尺,同一部位围岩受到循环爆破开挖的多次扰动普遍存在累积损伤。对乌东德水电站左岸导流洞爆破开挖过程中的爆破振动和围岩变形监测进行了监测和数值分析,基于累积损伤理论,通过引入损伤判据及损伤变量,考虑计算中产生的不同程度的损伤区域的岩体参数劣化,并将劣化后的参数引入相应损伤单元进行后续开挖爆破数值模拟计算,从而对岩体爆破开挖累积损伤效应进行模拟。通过比较乌东德水电站导流洞的实测数据以及数值模拟计算结果发现,考虑累积损伤的计算结果无论是爆破振动速度还是围岩变形均更接近于实测值。对爆破开挖的分析模拟中应考虑围岩的多次循环爆破累积损伤效应。 相似文献
15.
硬岩隧道开挖过程中的岩爆灾害与隧道围岩的应力状态密切相关，卸压爆破可减缓围岩体应力集中程度，是一种直接有效的岩爆防治措施。以巴陕高速公路米仓山隧道岩爆段卸压爆破为例，运用GDEM-BlockDyna(块体动力学仿真系统)软件进行考虑高地应力和岩体非均质性条件的隧道分步开挖数值模拟分析；将卸压爆破作为唯一变量，进行了两组方案(是否进行卸压爆破)的数值模拟对比分析，并结合微震监测数据，对隧道围岩卸压爆破效果进行检验。结果表明:在隧道围岩分步开挖过程(未进行卸压爆破)的模拟中，围岩出现起裂损伤，应力集中和局部裂纹贯通等现象，并可能诱发岩爆灾害；在围岩卸压爆破条件下，围岩应力集中以及损伤程度有所降低，岩爆风险得到抑制。对比两组模拟结果，损伤均集中于拱顶及拱底，损伤半径比值(卸压/未卸压)分别为3.4倍(拱顶)、1.47倍(拱底)，损伤体积比值(卸压/未卸压)为5.36倍，但区域最大损伤量值从1(未卸压)降低到0.6(卸压)，且围岩应力峰值降低约5 MPa，应力梯度降低0.8 MPa ·m-1，表明围岩仍具有自稳能力，岩爆发生风险降低。相关结果可为隧道高地应力围岩段实施卸压爆破和合理设计卸压爆破方式提供理论依据。 相似文献
16.
在地下隧道施工中遇到既有桩的情况并不少见,尽管近年来隧道--土--桩相互作用引起了广泛关注,但以往的研究主要集中在小规模隧道开挖引起的桩的反应上。通过三维离心模型试验,研究了双管大型隧道开挖引起的群桩变形机理。由于隧道开挖引起的应力释放,群桩的实测沉降随隧道的推进几乎呈线性增加。监测点距新建隧道较短,导致群桩沉降较大。单隧道开挖完成后,在隧道中心线正上方观测到最大桩群沉降为0.23%D(即隧道直径)。双管开挖后,最大群桩沉降增加到0.32%D,最大群桩沉降位置向两隧道之间的中心线移动。随着开挖面接近监测断面,既有桩群迅速向开挖面倾斜。当隧道工作面通过监测断面时,减少了现有群桩的倾斜。显然,当隧道工作面位于监测断面正下方时,测得的群桩倾斜达到最大值。这清楚地说明了隧道开挖引起群桩的三维变形机理。若将隧道开挖简化为二维问题,则忽略了群桩沿隧道纵向的倾斜,而群桩的倾斜位于非保守侧。 相似文献
17.
Mei Jie Zhang Wanzhi Xu Bangshu Zhu Yongxue Wang Bingkun 《Geotechnical and Geological Engineering》2021,39(7):5309-5323
For large cross-section tunnel in horizontal layered rock mass, blasting excavation often causes serious overbreak and underbreak. In this study, blasting excavation tests of tunnel upper face were conducted, blast-induced excavation damage and the influence mechanisms of weak beddings and joints were analyzed based on the Panlongshan tunnel. In order to achieve fine excavation, the cut mode of “center holes and four-wedge cutting holes”, the blasthole pattern of “empty holes, long holes, short holes and additional relief holes”, the maximum single-hole charge and the air-deck charge structure were proposed. Compared with the damage characteristics, overbreak and underbreak, and deformations of surrounding rock before and after optimization, the latter was better in tunnel contour formation and surrounding rock stability. The results show that after optimization, the large-area separation of vault rock mass is solved, the step-like overbreak of spandrel rock mass is reduced and the large-size rock block and underbreak are avoided. The maximum linear overbreak of vault, spandrel, and haunch surrounding rock is decreased by 42.3%, 53.7% and 45.1%, respectively. The underbreak at the bottom of the upper face is reduced from ??111.5 to ??16.5 cm. The average overbreak area is decreased by 61.1%. The surrounding rock displacement after optimization finally converges to the smaller value. The arch crown settlement and the horizontal convergence of haunch are reduced by about 21.6% and 18.3%, respectively. Furthermore, from the completion of blasting excavation to the stabilization of surrounding rock, it takes less time by using the optimized blasting scheme.
相似文献18.
Effect of Tunnel Shape and Support System on Stability of a Tunnel in a Deep Coal Mine in China 总被引：1，自引：1，他引：0
Zhengxing Yu Pinnaduwa H. S. W. Kulatilake Fuxing Jiang 《Geotechnical and Geological Engineering》2012,30(2):383-394
Stability level of tunnels that exist in an underground mine has a great influence on the safety, production and economic
performance of the mine. Ensuring of stability for soft-rock tunnels is an important task for deep coal mines located in high
in situ stress conditions. The aim of this study is to investigate the effect of tunnel shape and support pattern on the deformation,
failure zone and stability around a tunnel located in a coal rock mass in China and to select an appropriate tunnel shape
and a support pattern to provide a stable stress-deformation condition around the tunnel. Using the available information
on stratigraphy, geological structures, in situ stress measurements and geo-mechanical properties of intact rock and discontinuity
interfaces, a three-dimensional numerical model was built using the FLAC software to simulate the stress conditions around
the tunnel in the coal rock mass. Analyses were conducted for several tunnel shapes and rock support patterns. Results obtained
for the distribution of failed zones, and stress and displacement fields around the tunnel were compared to select the best
tunnel shape and support pattern to achieve the optimum stability conditions. Also, a comparison is given between the numerical
predictions and field deformation monitoring results. 相似文献
19.
Hossain Md. Shahin Teruo Nakai Kenji Ishii Toshikazu Iwata Shou Kuroi 《Acta Geotechnica》2016,11(3):679-692
To investigate the realistic ground behavior during tunneling, a new device has been developed. With the new device, model tests of tunnel excavation considering an existing tunnel and an existing building were carried out. Non-linear finite element analyses corresponding to the model tests were also conducted using FEMtij-2D software where an elastoplastic subloading t ij model was used to describe the mechanical behavior of soil. Earth pressure distribution around the tunnels and ground movements during tunnel excavation depend on the distance and position between the twin tunnels. There is a significant effect of tunneling on the existing foundation of building even in the case where the tunnel is constructed in deep underground. The numerical analyses capture well the results of the model tests. 相似文献