Tunnel seismic tomography method for geological prediction and its application

Typical existing methods of tunnel geological prediction include negative apparent velocity, horizontal seismic profile, and the Tunnel Seismic Prediction （TSP） method as this technology is under development at home and abroad. Considering simpler observational methods and data processing, it is hard to accurately determine the seismic velocity of the wall rock in the front of the tunnel face. Therefore, applying these defective methods may result in inaccurate geological inferences which will not provide sufficient evidence for classifying the wall rock characteristics. This paper proposes the Tunnel Seismic Tomography （TST） method using a spatial observation arrangement and migration and travel time inversion image processing to solve the problem of analyzing the velocity structure of wall rock in the front of the tunnel face and realize accurate imaging of the geological framework of the tunnel wall rock. This method is very appropriate for geological prediction under complex geological conditions.

Applications of Pre-Geological Prediction in Tunnel Construction

Pre-geological prediction (PGP) is defined as the prediction of engineering geologic condition and hy-drogeological condition certain distance ahead of the working face. The purpose of this paper is to introduce mainlygeologic survey before and in excavation, to clarify their emphasis on PGP. At the same time, the technique is appliedto an engineering case, the longest highway tunnel in Gansu province. Data of geological survey of outside tunnels,sound wave detection, and geologic sketch for both tunnel face and sidewalls within the tunnel are analyzed. Afteranalyzing these data, long-term pre-geological prediction forecasting basic geological conditions of fault 4 such aslithology, scope, location, etc., and short-term and more accurate pre-geological prediction are reported.

Application of Integrated Geological Prediction Technologies in Sub-river Tunnel of Liuyang

Because of the frequent serious geo-hazards met in constructing sub-river tunnels,the application of geological prediction is necessary to reduce the risk. Taking the Liuyang River Tunnel(10.1 km,with 362 m of the sub-river part) which is one of the key projects of the dedicated-passenger railway from Wuhan to Guangzhou as an example,the application of integrated geological prediction technologies is expounded in detail.The effects of TSP(tunnel seismic prediction) and infrared water detectors are analyzed as key points in order to summarize the advantages and disadvantages of these devices.The results of this research which can be adopted to improve the effects of the

Predicting geological hazards during tunnel construction

The complicated geological conditions and geological hazards are challenging problems during tunnel construction,which will cause great losses of life and property.Therefore,reliable prediction of geological defective features,such as faults,karst caves and groundwater,has important practical significances and theoretical values.In this paper,we presented the criteria for detecting typical geological anomalies using the tunnel seismic prediction（TSP） method.The ground penetrating radar（GPR） signal response to water-bearing structures was used for theoretical derivations.And the 3D tomography of the transient electromagnetic method（TEM） was used to develop an equivalent conductance method.Based on the improvement of a single prediction technique,we developed a technical system for reliable prediction of geological defective features by analyzing the advantages and disadvantages of all prediction methods.The procedure of the application of this system was introduced in detail.For prediction,the selection of prediction methods is an important and challenging work.The analytic hierarchy process（AHP） was developed for prediction optimization.We applied the newly developed prediction system to several important projects in China,including Hurongxi highway,Jinping II hydropower station,and Kiaochow Bay subsea tunnel.The case studies show that the geological defective features can be successfully detected with good precision and efficiency,and the prediction system is proved to be an effective means to minimize the risks of geological hazards during tunnel construction.

Tectonic evolution and the analysis of unfavorable geology in a tunnel

Based on the theory of geomechanics and using geologic analytical methods,analyed the fault characteristics, mechanical properties, displacement mode, tectonic system, structural pattern, activity mode of stress, tectonic activity, and tectonic evolution ofthe area of the Xiamen submarine tunnel, the strike NWW 295^(。), which is the main unfavorable geological structure that affects the safety of the tunnel construction; the macrogeological prediction concludes that weathered troughs and groundwater-rich zonesformed by its larger-scale fault fracture zones are the main unfavorable geological bodiesprovides a basis for preventing the geo-logical hazards in the tunnel construction.

Multi-source data integration and multi-scale modeling framework for progressive prediction of complex geological interfaces in tunneling

A reliable geological model plays a fundamental role in the efficiency and safety of mountain tunnel construction.However,regional models based on limited survey data represent macroscopic geological environments but not detailed internal geological characteristics,especially at tunnel portals with complex geological conditions.This paper presents a comprehensive methodological framework for refined modeling of the tunnel surrounding rock and subsequent mechanics analysis,with a particular focus on natural space distortion of hard-soft rock interfaces at tunnel portals.The progressive prediction of geological structures is developed considering multi-source data derived from the tunnel survey and excavation stages.To improve the accuracy of the models,a novel modeling method is proposed to integrate multi-source and multi-scale data based on data extraction and potential field interpolation.Finally,a regional-scale model and an engineering-scale model are built,providing a clear insight into geological phenomena and supporting numerical calculation.In addition,the proposed framework is applied to a case study,the Long-tou mountain tunnel project in Guangzhou,China,where the dominant rock type is granite.The results show that the data integration and modeling methods effectively improve model structure refinement.The improved model’s calculation deviation is reduced by about 10%to 20%in the mechanical analysis.This study contributes to revealing the complex geological environment with singular interfaces and promoting the safety and performance of mountain tunneling.

对提高TGP隧道地质预报系统准确性的分析

基于TGP预报系统探测原理及使用过程中存在的问题,指出在数据采集过程中产生异常信号的影响因素为外界脉冲信号干扰、电流干扰、不良耦合、管波干扰及装药质量,结合工程应用的反馈资料分析预报结论产生误差的原因,提出增强对异常地震波的认识、加强地质工作、注意边缘绕射波是根本解决措施,避免产生和接收异常信号,提高采集数据信息的质量,增加TGP预报系统数据信息解释的准确性和可靠性,促进了隧道地质预报技术水平的提高。

TGP二维与三维地质预报成果对比

以TGP超前地质预报理论和实际工程资料为基础,运用信息化逻辑方法对TGP二维与三维地质预报成果进行分析对比,主要从预报地质构造的位置、规模、围岩级别和产状四个成果比较二者的相同和不同之处。结果表明,对于隧道前方岩性无明显差异的围岩,二维与三维的地质预报结果基本相同;对于与隧道斜交的地质构造,二维与三维地质预报在构造产状预报结果上相近,但二维地质预报在围岩级别预测方面有利,三维地质预报在规模和位置的预报方面有利;对于与隧道激发炮孔连线一侧边墙不相交的地质构造,二维与三维地质预报结果基本不同,且三维比二维的地质预报结果有利。

TGP技术在复杂地质隧道施工中的应用实例分析

轨道交通六号线二期中梁山隧道2号隧道全长4 322m,地质条件复杂,主要不良地质条件有突水突泥、岩溶以及煤矿采空区。为确保工程施工安全,采用TGP206系统对其进行地质超前预报,并辅以地质雷达进行对比验证,提高预报的准确性,为隧道工程施工提供指导性依据。

TGP12型隧道地质预报仪在大坪隧道超前地质预报中的应用

随着工程等级的不断提高,在隧道开挖中遇到的地质环境越来越复杂,隧道地质超前预报在隧道开挖中的作用越来越显著。因此,如何选择有效的预报措施对隧道开挖中人员、设备的安全和隧道硐室的支护方式具有重要意义。主要介绍TGP12型隧道地质预报仪探测系统的原理、数据处理、解释技术和在大坪隧道施工中的超前预报应用。通过对比分析验证了预报结果的准确性,展示了TGP12型隧道地质预报系统在隧道施工地质超前预报中的广阔应用前景。

TGP206隧道地震波预报系统在某隧道施工中的运用与探讨

隧道施工中,探明掌子面前方地质情况,从而选择合理的施工工法和支护参数,直接关系到隧道施工的安全和效率。该文在介绍TGP206隧道地震波预报系统原理的基础上,结合重庆某隧道工程实例,对隧道施工过程中掌子面前方的地质情况进行预测,并通过与开挖后地质情况的对比分析,来检验预报结果的合理性。同时对TGP206超前地质预报结果准确性的影响因素进行探讨分析,总结出提高预报准确性的措施,为今后类似隧道工程提供参考。

TGP超前地质预报技术的隧道围岩精细化预报

针对目前TGP超前地质预报技术以波速分析为主,少见地质构造界面分析的现状,利用TGP实测二维和三维探测结果,从地层波速和地质构造界面2方面精细成功地预报了某隧道掌子面前方围岩地质情况及围岩级别,结果表明:1)在实际工作中,应严格按照TGP数据采集要求得到高质量的原始资料,才能做进一步数据处理和解译;2)TGP二、三维解译成果大体一致,但所反映细节存在差异,实际工作中应比对二、三维解译成果,研究其相似性和差异性,综合得出预报结果;3)TGP三维地质构造界面解译成果较二维可视化程度高,可直观反映构造界面的走向和倾向、明确构造界面与隧道开挖轮廓的关系。最后通过地质构造界面解译预测了隧道重点施工风险段落和部位,通过地层波速和地质构造界面的综合解译,为隧道动态设计施工提供了重要依据。

TGP在大坪山隧道地质预报中的应用效果分析

大坪山隧道是谷竹高速公路的一座特长隧道,穿越区域性的青峰断裂带,且地质构造复杂、断层破碎带多,进行超前地质预报是隧道安全施工的重要保障。本文介绍了TGP超前地质预报系统的基本原理和主要技术优势,并通过实例分析了TGP在大坪山隧道不同地层中的预测效果。结果表明:软岩中尤其是在没有大规模不良地质体的岩层中,TGP的探测结果与实际情况稍有出入;但在断层破碎带等与围岩介质波阻抗差别较大的不良地质体的岩层中,TGP的预测结果比较准确。同时,指出TGP作为一种物探手段,应在地质调查分析的基础上,结合其他技术手段,以提高地质预报的效果。

TGP超前预报系统在岩溶隧道中的实践应用

在岩溶地区修建隧道,经常会遇到溶洞、暗河、突水、突泥等地质灾害,给施工带来巨大损失。介绍了TGP系统的基本工作原理、数据采集和处理过程。与其它预报方法相比,TGP在准确性和预报距离以及可操作性等具有一定的优势,本文基于TGP系统对城(口)万(源)快速公路通道八台山隧道进口避难通道溶洞进行了预报,通过TGP系统软件得到深度偏移图、同侧综合预报成果图、3D横断面扫描图等,通过分析波速、反射界面等,均证实了有溶洞存在,仪器测出的各项数据相互验证,具有一定的互补性,同时也具有一定的准确性。对照实际开挖情况,验证分析了该系统的实用性和可信性以及在指导施工方面所起的重要作用,这对于促进TGP系统在我国工程界的运用起到一定的推动作用。

TGP隧道地震波预报系统与技术

隧道工程是铁路、公路和水利水电等大型项目中的重要工程,因地质条件不明造成隧道施工事故的危害是巨大的,加强隧道施工地质超前预报工作是非常必要的。国内外对隧道地震波超前预报技术已研究多年,笔者就这方面的现状及及问题进行了讨论,指出了TSP技术存在的不足,阐述了克服盲目性、提高科学预报的重要性,介绍了新开发的TGP隧道地震预报系统与技术及应用效果。

TGP在云山隧道地质超前预报中的应用

介绍了TGP-206的工作原理及测线测点布置方法,并通过云山隧道实例,分析了TGP-206在地质预报中的可靠性和适用性,以促进TGP-206在类似隧道地质超前预报中的推广应用。

TGP206在隧道超前地质预报中的应用

隧道是铁路、公路、水电等建设项目中的重要工程,水文地质条件是影响隧道施工进度的重要因素。为了准确探测隧道路线经过区域的水文条件,确定合理的围岩级别、支护参数,采取相应的防护措施,通常选择超前地质预报系统。TGP在隧道超前地质预报中应用广泛,为了提升应用技能。本文以大尖山隧道工程为例,探讨TGP在隧道工程施工中的具体应用,提出要加强超前地质预报工作,还需要采用合理有效的组合手段。为类似建设项目提供经验借鉴。

TGP-206在洞宫山隧道地质超前预报中的应用

简要介绍了隧道地质超前预报,简述了TGP-206工作原理和实际应用,结合工程实例,证明了TGP-206在隧道地质超前预报中的实用性和有效性,以期促进TGP-206在类似隧道地质超前预报中的应用。

地质雷达和TGP地震波法在高家坪特长隧道岩溶探测中的应用

近年来,随着西部大开发战略的进一步实施,西部地区成为国家建设的重点,西南岩溶地区的铁路工程、高速公路在施工过程中常常会遇到复杂多变的岩溶地形及赋存丰富的岩溶地下水,给隧道工程安全构成重大威胁。本次研究以宜城至保康段高速公路中的高家坪隧道Zk45+705~Zk45+845隧道段为研究对象,前期岩溶水文地质调查结果显示,该隧道段存在岩溶突水突泥的风险。首先通过地质雷达法探明Zk45+725~Zk45+735隧道段岩体节理裂隙及溶洞发育;然后通过TGP(Tunnel Geology Prediction)地震波法进一步探测隧道底板岩溶发育情况。结果表明,本次研究通过地质雷达、TGP相结合的物探方法成功地探测了研究工区高风险岩溶发育情况,并据此提出了隧道溶洞处置以及防排水工程设计方案,可为今后的实际施工提供指导。

TGP地震预报技术在隧道超前地质预报中数据异常原因分析及处理措施

隧道施工常采用地震反射波法采集地震波数据,受施工进度、地质情况、现场配合、操作人员水平等因素限制,使得很多采集到的数据出现异常。为提高数据采集质量,避免出现异常数据,通过TGP地震预报技术在铁路隧道工程中的应用实践,从触发与装药、电压(流)干扰、耦合不良、隧道管波、岩性变化5方面分析总结异常数据出现的原因,并提出相应的处理措施:1)提高装药质量;2)远离高压电缆及设备;3)保证成孔质量;4)做好注水和堵孔;5)重视基础地质工作。通过采取以上措施,达到准确预报前方地质情况的目的。