Numerical Simulation of Surrounding Rock Deformation and Grouting Reinforcement of Cross-Fault Tunnel under Different Excavation Methods

Tunnel construction is susceptible to accidents such as loosening, deformation, collapse, and water inrush, especiallyunder complex geological conditions like dense fault areas. These accidents can cause instability and damageto the tunnel. As a result, it is essential to conduct research on tunnel construction and grouting reinforcementtechnology in fault fracture zones to address these issues and ensure the safety of tunnel excavation projects. Thisstudy utilized the Xianglushan cross-fault tunnel to conduct a comprehensive analysis on the construction, support,and reinforcement of a tunnel crossing a fault fracture zone using the three-dimensional finite element numericalmethod. The study yielded the following research conclusions: The excavation conditions of the cross-fault tunnelarray were analyzed to determine the optimal construction method for excavation while controlling deformationand stress in the surrounding rock. The middle partition method (CD method) was found to be the most suitable.Additionally, the effects of advanced reinforcement grouting on the cross-fault fracture zone tunnel were studied,and the optimal combination of grouting reinforcement range (140°) and grouting thickness (1m) was determined.The stress and deformation data obtained fromon-site monitoring of the surrounding rock was slightly lower thanthe numerical simulation results. However, the change trend of both sets of data was found to be consistent. Theseresearch findings provide technical analysis and data support for the construction and design of cross-fault tunnels.

Coseismic deformation and fault slip distribution of the 2023 M_(W)7.8 and M_(W)7.6 earthquakes in Türkiye

On February 6,2023,a devastating earthquake with a moment magnitude of M_(W)7.8 struck the town of Pazarcik in south-central Türkiye,followed by another powerful earthquake with a moment magnitude of M_(W)7.6 that struck the nearby city of Elbistan 9 h later.To study the characteristics of surface deformation caused by this event and the influence of fault rupture,this study calculated the static coseismic deformation of 56 stations and dynamic displacement waveforms of 15 stations using data from the Turkish national fixed global navigation satellite system(GNSS)network.A maximum static coseismic displacement of 0.38 m for the M_(W)7.8 Kahramanmaras earthquake was observed at station ANTE,36 km from the epicenter,and a maximum dynamic coseismic displacement of 4.4 m for the M_(W)7.6 Elbistan earthquake was observed at station EKZ1,5 km from the epicenter.The rupture-slip distributions of the two earthquakes were inverted using GNSS coseismic deformation as a constraint.The results showed that the Kahramanmaras earthquake rupture segment was distinct and exposed on the ground,resulting in significant rupture slip along the Amanos and Pazarcik fault segments of the East Anatolian Fault.The maximum slip in the Pazarcik fault segment was 10.7 m,and rupture occurred at depths of 0–15 km.In the Cardak fault region,the Elbistan earthquake caused significant ruptures at depths of 0–12 km,with the largest amount of slip reaching 11.6 m.The Coulomb stress change caused by the Kahramanmaras earthquake rupture along the Cardak fault segment was approximately 2 bars,and the area of increased Coulomb stress corresponded to the subsequent rupture region of the M_(W)7.6 earthquake.Thus,it is likely that the M_(W)7.8 earthquake triggered or promoted the M_(W)7.6 earthquake.Based on the cumulative stress impact of the M_(W)7.8 and M_(W)7.6 events,the southwestern segment of the East Anatolian Fault,specifically the Amanos fault segment,experienced a Coulomb rupture stress change exceeding 2 bars,warranting further attention to assess its future seismic hazard risk.

Deformation field around a thrust fault:A comparison between laboratory results and GPS observations of the 2008 Wenchuan earthquake

On May 12,2008,an Mw7.9 earthquake occurred in Wenchuan County,Sichuan Province,China.Movement of Yingxiu–Beichuan Fault in the Longmenshan Fault Zone was considered to be the main cause of the earthquake.Earthquakes are closely related to fault activities.Therefore,studying the strain distribution and evolution process around active fault zones is important to the understanding of seismic activities.In this study,we conduct laboratory experiments with uniaxial compression applied to marble sheets with intentionally fabricated cracks.The speckle patterns of the rock samples under different loading conditions are recorded in real time by a digital camera.To calculate the deformation fields of the deliberately cracked marble sheets during different stages of the loading processes,the recorded images are processed by the digital image correlation method.The distribution and variation of the displacement and strain are further analyzed in order to understand the strain localization of and observed damage in the experimental fracture zones.Finally,we compare these laboratory results with the GPS-observed coseismic displacements during the 2008 Wenchuan earthquake,to assess the consistency between our laboratory observations and the field observations of the earthquake,but also to suggest how laboratory results can improve thinking about how earthquake patterns do and do not reflect fault patterns.

In-situ observation on the deformation behaviors of Fe-Mn-C TWIP steel

The microstructure and crack behaviour of twinning induced plasticity （TWIP） steel during tensile deformation was investigated with in-situ scanning electron microscopy （SEM）. The results show that there are two modes of plastic deformation during tensile test in the Fe-Mn-C TWIP steel： dislocation gliding and deformation twins. During the process of tensile deformation, secondary deformed twins are found. Inclusions have played a role in the course of ductile fracture, and microcracks initiate from inclusions and twin-twin intersections.

Hot ductility of DSS and its microstructure observation during hot deformation

selecting several typical DSS 00Cr22Ni5Mo3N,00Cr21Ni2Mn5N and 00Cr25Ni7Mo4N as research materials,hot ductility characteristic of DSS was studied and microstructure evolution during hot compression was observed.The results show that the optimum hot ductility temperature range of DSS is 1 050~1 200℃.00Cr25Ni7Mc4N exhibits the worst hot ductility and 00Cr21Ni2Mn5N has similar hot ductility to 00Cr22Ni5Mo3N.During hot compression,austenite of DSS mainly occurs dynamic recovery,the ferrite of 00Cr22Ni5Mo3N,00Cr21Ni2Mn5N can perform dynamic recovery and recrystallization,but only dynamic recovery can be observed in the ferrite of 00Cr25Ni7Mo4N.

Analyses on normal background characteristics about deformation observation data on the basis of wavelet transform method

Wavelet transform method is applied to measure time-frequency distribution characteristics of digital deformation data and noise. Based on the characteristics of primary modulus and stochastic white noise discrimination factor of wavelet decomposition, we analyze the variation rule of normal background and noise data from Shandong digital deformation observation data. The research results indicate that: a) 1/4 daily wave, semi-diurnal tide wave, daily wave and half lunar wave and so on quasi-periodic signal exist in the detail decomposing signal of wavelet when scale are equal to 2, 3 and 4; b) The amplitude of detail decomposing signal is the biggest when scale is equal to 3; c) The detail decomposing signal contains mainly noise corresponding to scale 1 and 5, respectively; d) We may trace the abnormal precursory which is related to earthquake by analyzing non-earthquake wavelet decomposing signal whose scale is specified from digital deformation observation data.

Study on the Cap Rock Deformation of Hutubi Underground Gas Storage by GPS Observations

The deformation responses of surface cap rocks of Underground Gas Storage( UGS) in Hutubi,Xinjiang during gas injection and production were investigated with the GPS data recorded by the deformation monitoring network,which includes 13 observation sites. The time series of three-dimensional deformation of the surface cap rocks was obtained in the UGS operation process,and the deformation signals in different phases were identified by combining the GPS data with wellhead pressure data. The results show that the respiration response of surface cap rock deformation is obvious during gas injection and production of UGS,and the surface deformation due to a 1MPa change of wellhead pressure is 1. 02 mm in gas injection and 1. 24 mm in gas production horizontally, and- 1. 11 mm in gas injection and 0. 86 mm in gas production vertically.

The Practice and Analysis of High-rise building Deformation Observation

This article first introduces the basic knowledge of the deformation measurement, discusses the causes and types of building deformation, tasks of deformation observation as well as its contents, methods, principles, process, and describes the main functions and contents of the deformation monitoring. In particular, this thesis describes the building settlement observation specifically and in great detail. It has carried out the analysis and research on the deformation measurement level of the building subsidence, as well as put forward requirements on the benchmark, layout and observation. Then referring to Shen Tie victory home 9 # building settlement measurement data and process, this paper explains the settlement observation level of Shen Tie victory home 9 # building level of choice and observation methods for embedding field bench mark and observation point thus to determine the subsidence and sedimentation rate.

Deformation Evolution Characteristics Revealed by GPS and Cross-fault Leveling Data before the M_S8. 0 Wenchuan Earthquake

Based on GPS velocity during 1999-2007,GPS baseline time series on large scale during1999-2008 and cross-fault leveling data during 1985-2008,the paper makes some analysis and discussion to study and summarize the movement,tectonic deformation and strain accumulation evolution characteristics of the Longmenshan fault and the surrounding area before the MS8. 0 Wenchuan earthquake,as well as the possible physical mechanism late in the seismic cycle of the Wenchuan earthquake. Multiple results indicate that:GPS velocity profiles show that obvious continuous deformation across the eastern Qinghai-Tibetan Plateau before the earthquake was distributed across a zone at least 500 km wide,while there was little deformation in Sichuan Basin and Longmenshan fault zone,which means that the eastern Qinghai-Tibetan Plateau provides energy accumulation for locked Longmenshan fault zone continuously. GPS strain rates show that the east-west compression deformation was larger in the northwest of the mid-northern segment of the Longmenshan fault zone,and deformation amplitude decreased gradually from far field to near fault zone,and there was little deformation in fault zone. The east-west compression deformation was significant surrounding the southwestern segment of the Longmenshan fault zone,and strain accumulation rate was larger than that of mid-northern segment.Fault locking indicates nearly whole Longmenshan fault was locked before the earthquake except the source of the earthquake which was weakly locked,and a 20 km width patch in southwestern segment between 12 km to 22. 5 km depth was in creeping state. GPS baseline time series in northeast direction on large scale became compressive generally from 2005 in the North-South Seismic Belt,which reflects that relative compression deformation enhances. The cross-fault leveling data show that annual vertical change rate and deformation trend accumulation rate in the Longmenshan fault zone were little,which indicates that vertical activity near the fault was very weak and the fault was tightly locked. According to analyses of GPS and cross-fault leveling data before the Wenchuan earthquake,we consider that the Longmenshan fault is tightly locked from the surface to the deep,and the horizontal and vertical deformation are weak surrounding the fault in relatively small-scale crustal deformation. The process of weak deformation may be slow,and weak deformation area may be larger when large earthquake is coming. Continuous and slow compression deformation across eastern Qinghai-Tibetan Plateau before the earthquake provides dynamic support for strain accumulation in the Longmenshan fault zone in relative large-scale crustal deformation.

Characteristics of regional crustal deformation before 2016 Menyuan Ms6.4 earthquake

On January 21, 2016, a strong earthquake with a magnitude of Ms6.4 happened at Menyuan, Qinghai Province of China. In almost the same place, there was another strong earthquake happened in 1986, with similar magnitude and focal mechanism. In this paper, we analyze the characteristics of regional crustal deformation before the 2016 Menyuan Ms6.4 earth- quake by using the data from 10 continuous Global Positioning System （GPS） stations and 74 campaign-mode GPS stations within 200 km of this event： （a） Based on the velocity field from over ten years GPS observations, a regional strain rate field is calculated. The results indicate that the crustal strain rate and seismic moment accumulation rate of the Qilian- Haiyuan active fault, which is the seismogenic tectonics of the event, are significantly higher than the surrounding regions. In a 20 km~ 20 km area around the seismogenic region, the maximum and minimum principal strain rates are 21.5 nanostrain/a （NW-SE extension） and -46.6 nanostrain/a （NE-SW compression）, respectively, and the seismic moment accumulation rates is 17.4 Nm/a. The direction of principal compression is consistent with the focal mechanism of this event. （b） Based on the position time series of the continuous GPS stations for a time-span of about 6 years before the event, we calculate the strain time series. The results show that the dilatation of the seismogenic region is continuously reduced with a ＂non-linear＂ trend since 2010, which means the seismogenic region has been in a state of compression. However, about 2-3 months before the event, both the dilatation and maximum shear strain show significant inverse trends. These abnormal changes of crustal deformation may reflect the non-linear adjustment of the stress-strain accumulation of the seismogenic region, when the accumulation is approaching the critical value of rupture.

Regional fault deformation characteristics before and after the Menyuan Ms6.4 earthquake

This study analyzes data regarding cross-fault deformations within the seismogenic zone of the 2016 Qinghai Menyuan Ms6.4 earthquake and its surrounding area. The results showed that the tendency anomaly sites near the epicenter had relatively long anomaly durations prior to the earthquake, while sudden-jumping anomaly sites started to increase in the middle eastern Qilian Mountains approximately a year before the earthquake and continued to increase and migrate towards the vicinity of the epicenter two to six months before the earthquake. Intensive observations a few days after the earthquake indicated that abnormal returns and turns before the earthquake were significant, but all had small amplitudes, and the coseismic effect was generally minor. In addition, the post-seismic tendency analysis of individual cross faults in the Qilian Mountain fault zone revealed an accelerating thrust tendency at all cross-fault sites in the middle Qilian Mountains after the 2008 Wenchuan Ms8.0 earthquake. This indicates that the Wenchuan mega-earthquake exerted a great impact on the dynamic environment of the northeastern margin of the Qinghai-Tibet plate and significantly enhanced the extrusion effect of the Indian plate on the middle Qilian Mountains, generating favorable conditions for the occurrence of Menyuan thrust earthquakes.

Experimental Researches on the Accuracy of Micro- Electromechanical Accelerometer-Array in Seafloor Failure Deformation Measurement

At present,there are few technologies applied to in situ observation of seabed deformation,among which the micro-electromechanical accelerometer-array(hereinafter referred to as accelerometers array)is a very advantageous measurement method,with both commercial products and successful application cases.However,the coupling effect between accelerometer-array and sur-rounding soil and the linkage effect of accelerometer-array itself during the deformation may influence the accuracy and reliability of the measurement data.A simulation test chamber was designed and processed,and four groups of simulation tests were carried out to explore the coupling effect and linkage effect of accelerometer-array in the soil with different degree of consolidation.The results show that the accelerometer-array and the soil coupled well,and the coupling effect is positively correlated with the degree of soil consoli-dation.The ratio of accumulative deviation to soil lateral deformation is high at the initial stage of deformation(0-50 mm)and reduced with the continuous increase of deformation(>100 mm).In the process of liquefied soil deformation,the linkage effect of accelerometer array can be ignored,and is negatively correlated with the degree of soil consolidation.A concept to improve the measurement accu-racy of accelerometer-array in different seafloor failure deformation modes is proposed.The research results provide references for the modification of accelerometer-array and the improvement for other flexible rod-shaped deformation sensors.

GPS Observation and Study on Recent Crustal Movement in the Northeastern Area of Pamir,Xinjiang

Calculation of repeated observation data at the densified GPS monitoring network in northeastern area of Pamir together with data from IGS stations in the periphery of the area yielded the movement rate of more than 40 GPS station sites in the area, and, hence, the recent crustal deformation rate pattern and time series of fiducial GPS stations in the area were obtained. The result indicates that the principal movement direction of the GPS station sites is NNW, basically diagonal to the strike of Tianshan fold belt, i.e. a normal compression occurs in the Tianshan region. The movement pattern near Jiashi and its southwestern zone is some different from that of station sites in their surrounding areas, indicating a certain relation of tectonic deformation in Jiashi area to seismic activity during last years. The movement rate of station sites in the periphery of Tarim basin less varies and its direction is basically consistent. It indicates less or basically no deformation within Tarim basin.

The Present Space-Time Motion and Deformation Features of the Northeastern Margin of the Qinghai-Xizang(Tibet) Block and Its Adjacent Area

On the basis of Discontinuous Deformation Analysis (DDA), and considering the moderate intrusion of specific block boundaries to different extents, the first-order block motion model is established for the northeastern margin of Qinghai-Xizang(Tibet) block and the kinematical model for depicting deformation of small regions as well by using GPS observations of three periods (1991, 1999 and 2001). By simulating, we obtained the motion features of the first-order blocks between the large WWN faults on the sides of the studied region, the distribution features of the principal strain rate field and the inhomogeneous motion features with space-time of the faults in the northern boundary of the Qinghai-Xizang (Tibet) block.

莆田地震台铟瓦棒伸缩仪故障分析及维修技术研究

该文论述莆田地震台形变观测仪器SS-Y型铟瓦棒伸缩仪近几年来的故障,从电源、主机、传感器、线路故障等几个方面对故障进行整理、分类、统计。通过故障的表现形式分析故障原因,整理出不同故障曲线形态产生的原因。总结莆田地震台维修经验,结合其他台站经验,针对不同故障给出维修方案,可为其他相关地震台站提供借鉴。

岩石破坏位移协调系数与GNSS数据的地震预测方法研究

本文以小尺度的岩石破坏试验为基础, 提出了以岩石表面多点位移信息预测岩石失稳破坏的短临前兆指标-位移协调系数(DCC).基于GNSS数据, 分析了DCC指标在大尺度地震中的演化特征, 提出了基于GNSS数据的DCC指标地震预测方法.研究结果表明: 在岩石弹性承载阶段, DCC在较低水平波动;当承载达到岩石峰值强度95%~99%时, DCC出现突增是预测岩石失稳破坏的重要前兆指标.通过大量试验统计, 确定了岩石从弹性变形到塑性变形转变的岩石弹塑性临界阈值范围为0.98±0.2.当DCC大于弹塑性临界阈值时, 岩石即将发生失稳破坏.基于GNSS数据计算获取三个地震案例震前的DCC指标与岩石破坏过程中DCC指标的演化特征具有相似性, 当DCC指标达到弹塑性临界阈值后大地震将在3~16天发生, 验证了将DCC指标作为预测地震发生短临前兆的有效性.同时, 地震发生区域可以利用震前GNSS数据绝对变形场重构方法通过异常变形区进行确定, 且根据DCC达到阈值时刻的异常变形区面积与地震震级呈对数关系, 可估算地震震级.研究结果对基于GNSS数据建立和完善地震短临预测方法具有重要的意义.

地震亚失稳过程中前兆异常演化的综合解释——以2014年鲁甸6.5级地震为例

文中以2014年鲁甸6.5级地震为例,在亚失稳实验及理论指导下,基于震前地震活动及地球物理观测资料并结合地震成核数值模拟结果,综合分析前兆异常时空演化与亚失稳过程的关系,首次提供了一个可明确佐证亚失稳阶段震源区成核、震源区附近协同化过程持续加剧的典型震例和观测事实。研究结果显示,依据大区域强震活动及流动重力观测,可判定鲁甸地震前研究区已处于高应力状态。在高应力背景判定的基础上,依据地震活动及地球物理观测前兆异常,可粗略判定鲁甸地震亚失稳过程可能起始于震前7、8个月,最突出的现象或判定指标是由震中附近小地震活跃所表征的断层应力状态由积累为主向释放为主的转变,以及由定点地球物理观测异常数量显著增加所表征的断层运动协同化现象,从地震成核的角度与成核后期核心弱化区扩张过程有关。之后至主震发生,还有2个时间节点需要关注:一是震前4、5个月,定点地球物理观测异常空间分布范围自震中附近向外围的明显扩展,显示断层变形的加速协同化;二是震前2个月之后,震中附近小地震活动开始减弱、微震活动及定点地球物理异常出现向震中的迁移收缩,与地震成核过程核心弱化区扩展之后的收缩过程相关联。

宁夏定点形变观测自然环境干扰分析

选取宁夏地区2015—2018年定点形变观测数据进行跟踪分析,初步探索自然环境典型干扰事件在形变观测数据中的特征表现形式,旨在丰富宁夏地震前兆数据服务产品,为形变观测数据的干扰识别提供参考依据,为深入研究等提供基础数据。

隧道浅埋段穿越软弱复杂地层加固处理技术

某隧道进口浅埋段穿越风化砂、细角砾土和碎石土层,局部夹有软粉质黏土和块石,围岩自稳能力差,隧底局部承载力不足。介绍穿越软弱复杂地层加固动态处理技术,通过采用地表注浆加固、洞外增设第2层超长管棚、优化CRD工法等措施,实施隧道超前周边注浆、隧底钢管桩注浆等加固处理技术,确保施工安全和结构安全。

海宁山洞地形变台建设总结与思考

海宁硖石地震台位于浙江海宁市硖石街道西山公园人防山洞内,该台在建设过程中,不但面临岩石体质量差的问题,洞室地面下挖至2 m以上深度,岩石依旧呈现多气孔且破碎的状态;还面临洞室湿度高的问题(>95%Rh)。最终在不可能采用岩石墩建台的情况下,通过浇筑大面积混凝土仪器墩,并对洞室环境进行改造,降低洞室湿度,做到保温、恒湿,改善观测环境。至今,该台已有十多年的运行时间,从目前情况看,台站观测数据平稳连续,固体潮清晰,达到了台站改造的预期效果。本文通过总结海宁硖石地震台在改造过程中取得的经验,为在一些不具备建造岩石墩的人防、民用山洞内,建设地形变观测台提供借鉴。