罗湖断裂带地应力场数值模拟分析

根据深圳地区地应力的实测资料,通过最优化算法,模拟整个深圳区域的地应力场.将计算结果作为罗湖地区计算区域位移的边界条件,进一步模拟罗湖断裂带的区域地应力场,研究了罗湖断裂带所在区域的地应力场大小、方向、变化规律和断层活动特征,为该区域主要建筑物的地面变形稳定性评价提供参考.     

煤层底板断裂突水时间弱化效应机理的仿真模拟研究—以开滦赵各庄煤矿为例

采用现场地应力实测、室内不同含水量情况下的断裂带物质的单轴、三轴常规和流变力学试验以及弹塑性三维可视化数值仿真模拟（FLAC^3D)等研究，获得了断裂带物质弱化效应力学参数，阐述了其弱化机理和主要控制因素，提出了煤层底板断裂构造突水时间弱化效应的新概念。对赵各庄矿13水平（－1100m)F8断层破碎带穿越的首采区安全回采方案做出了预测和评价。     

黄河黑山峡大柳树坝址区F201和F7(8)断层的活动性

黄河黑山峡大柳树坝址区位于青藏高原中卫-同心活动断裂带内F7(8)和F3断层所夹持的寒武系变质砂岩夹千枚岩推覆岩片中。对F201、F7(8)断层活动性的认识是坝址稳定性评价的关键，也是争议的焦点。通过对大柳树坝址区F201、F7(8)断层带特征的追索观测、工程揭露和断层泥测年，获得F201、F7(8)断层活动特征的新资料，证实了F201断层是一条晚更新世晚期和全新世以来强烈活动的区域发震断层，同时确定了7(8)断层水平左旋走滑作用的存在；发现断层通过之处二级阶地堆积物的震陷槽；获得了小于20ka断层泥测年数据，尤其是确定了7(8)断层与F201断层的交会地点。因此，按水电规范，F201和F7(8)断层被定为活动断层。     

三峡工程二期围堰运行期变形特性研究

基于土石坝分析的DuncanE-μ本构模型，研究了土石坝分析的3参量流变模型，并编制了围堰流变分析程序。根据三峡工程二期围堰运行前期的部分实测变形数据，反演分析了流变分析所需的计算参数。流变分析表明，三峡工程二期围堰结构的水平和垂直流变变形存在时间上的不同步性，垂直流变位移的稳定时间在堰体结构施工完成后的6个月左右，而水平流变位移的稳定时间只需要3个月。围堰结构的后期流变位移平均值是流变初期时位移的2～3倍。     

深圳断裂带现今构造活动性及其对深圳市输水隧洞工程地壳稳定性影响

从微震活动、断层位移监测、现今地应力测量等方面进行深圳断裂带现今构造活动性分析, 配合构造应力场三维数值模拟, 定量计算了深圳断裂带与输水隧洞交汇部位的现今活动量级范围以及输水隧洞不同地段轴向与最大水平主压应力夹角, 推算出深埋输水隧洞地段现今构造应力状态, 并结合地震活动性及其危险性、岩土体稳定性等研究成果, 运用模糊数学方法, 评价输水隧洞工程地壳稳定性, 为工程设计和施工提供依据.      

古新世以来郯庐断裂的位移量及其对莱州湾凹陷的控制

高分辨三维地震可视化及方差切片分析显示,郯庐断裂渤海海域莱州湾段北北东向断裂系发育。断层在水平方差切片上的拖拽现象、断裂带内部断层的组合关系以及凹陷沉积中心的迁移等,表明古新世以来该区存在右旋走滑运动。假设在东、西两支断层的走滑拉分作用下,根据可容纳空间不变原理,设计了三角形模型、长方形模型、半地堑型模型以及地堑型模型共四种模型,计算莱州湾凹陷南北长度和凹陷深度的关系,其中半地堑模型计算得到的郯庐断裂的水平位移为7km。结合断层的平面分布和断层的切割关系,表明古新世以来郯庐断裂的走滑拉分作用难以控制莱州湾凹陷的形成,走滑拉分作用只是在走滑断裂带内部形成了局部小型洼地,其规模很小,影响非常有限。     

煤柱挖潜影响下断层活化FLAC3D数值模拟研究

为研究断层防水煤柱挖潜对断层的影响,分析断层活化的危险性,应用FLAC3D数值模拟分析软件,以荆各庄矿1196F工作面开采挖潜F3断层防水煤柱为原型,对煤柱挖潜影响下F3断层活化进行了数值模拟分析。研究表明:F3断层防水煤柱的挖潜,打破了原有的应力平衡,在一定程度上影响了断层带内的应力分布,致使断层上下盘的应力增量和位移显著不同,并在工作面斜上方断层带内产生了剪应力变形增量集中,该位置最易引发断层活化,但由于F3断层挖潜后还剩60m宽度,煤柱挖潜对F3断层的影响是局部的,没有引起断层带内物质产生剪切破坏,F3断层没有产生活化。该结论得到了物探和钻探成果的验证。     

建立在雷达卫星影像判读基础上四川龙门山断裂晚第四纪活动特征研究

介绍了应用雷达卫星影像对四川龙门山活动断裂开展断错地貌判读结果,展示了龙门山构造带4条分支断裂9个点位的雷达卫星影像图像、11个点位的野外调查结果及6个点位与断层活动性有关的地层测年。在11个野外调查点位中,位于青城山北面4条断裂8个点位均出现2008年5.12汶川MS8.0地震的地表破裂,其中包括沿青川断裂青溪段及金山寺断层沟谷出现的两条地表破裂,沿后山断裂带茂县北断层和汶川南七盘沟断层出现的地表破裂;   沿中央断裂带北川和小鱼洞南2个点位出现的地表破裂;   以及沿前山断裂汉旺台地前缘和青城山山前地表破裂点位。在这些地表破裂中,中央断裂带地表垂直位移为 2～6m,青川断裂、后山断裂和前山断裂多数段地表断错垂直位移量为 10～40cm。后者位移量虽小,也不应被忽视。本项研究结果表明,雷达卫星影像显示青川断裂与后山断裂带和中央断裂带右旋走滑明显。雷达卫星影像实地调查表明,前山断裂带南段的水口场－横山庙断裂带醒目的断错地貌引人注目。     

向家坝水电站地下厂房围岩稳定的黏弹塑性有限元分析

考虑流变作用,建立三维有限元模型进行数值计算,以洞室变形和点抗滑安全系数为指标,针对向家坝水电站地下厂房围岩的特殊性进行稳定性研究,结果表明,随着围压的增高,流变速率逐渐减小,初始应变逐渐减小;软弱夹层处流变速率较其他岩体减小缓慢,且开挖后流变达到稳态状态时软弱夹层最终流变位移较大;黏弹塑性下围岩位移分布及变化规律与弹塑性一致,但黏弹塑性下计算位移明显要比弹塑性大;流变效应对岩体变形和稳定性,以及对支护结构有重要影响;黏弹塑性情况下,洞室围岩特征点抗滑安全系数比弹塑性条件下小,软弱夹层出露处和拱顶点抗滑安全系数较低,点抗滑安全系数分析还表明,软弱夹层对其稳定性影响明显,验证了位移分析结果。     

西藏邦铺矿区花岗岩剪切流变本构研究及其开挖边坡长期稳定性分析

岩体的破坏主要是沿着破坏面滑移的压剪破坏,对西藏邦铺矿区花岗岩岩样进行不同法向应力下的剪切流变试验。通过分析其剪切流变试验曲线,并基于Burgers模型,引入了一种改进非线性牛顿体黏壶,进而提出了一种改进的Burgers剪切流变模型,并利用该流变模型辨识的参数,应用于西藏邦铺矿区开挖边坡长期稳定性分析。结果表明：（1）改进的Burgers剪切流变模型,能够很好地拟合岩石流变的3阶段,对加速流变阶段的拟合结果很理想,具有较好的实用性;（2）开挖边坡稳定性分析时,考虑流变长期作用后,开挖边坡中部台阶区域位移变大,应力也发生变化,应加强该区域的支护和预警措施。     

断层带岩体变形模量对坝基稳定性影响

变形模量是表征断层带岩体力学性能的一个重要参数,而断层带岩体变形模量与其所处的环境有密切关系。以理论分析和现场试验为基础,以三维数值分析技术为主要研究手段,结合大型水电工程实例,对断层带岩体变形模量对坝基整体稳定性影响进行了分析研究。研究结果表明：大坝建成水库蓄水以后,在未受到库水渗透影响的前提条件下,位于坝基部位的断层带岩体变形模量会有一定程度的增大。断层带变形模量从0.6 GPa一直增加到4.0 GPa,使得断层带岩体所在坝段关键点水平位移降低0.544~0.846 mm、垂直位移降低1.190~2.232 mm、最大拉应力降低0.06 MPa,有利于提高大坝的整体稳定性。     

Quaternary crustal deformation along a major branch of the San Andreas fault in central California

Deformed marine terraces and alluvial deposits record Quaternary crustal deformation along segments of a major, seismically active branch of the San Andreas fault which extends 190 km SSE roughly parallel to the California coastline from Bolinas Lagoon to the Point Sur area. Most of this complex fault zone lies offshore (mapped by others using acoustical techniques), but a 4-km segment (Seal Cove fault) near Half Moon Bay and a 26-km segment (San Gregorio fault) between San Gregorio and Point Ano Nuevo lie onshore.At Half Moon Bay, right-lateral slip and N—S horizontal compression are expressed by a broad, synclinal warp in the first (lowest: 125 ka?) and second marine terraces on the NE side of the Seal Cove fault. This structure plunges to the west at an oblique angle into the fault plane. Linear, joint0controlled stream courses draining the coastal uplands are deflected toward the topographic depression along the synclinal axis where they emerge from the hills to cross the lowest terrace. Streams crossing the downwarped part of this terrace adjacent to Half Moon Bay are depositing alluvial fans, whereas streams crossing the uplifted southern limb of the syncline southwest of the bay are deeply incised. Minimum crustal shortening across this syncline parallel to the fault is 0.7% over the past 125 ka, based on deformation of the shoreline angle of the first terrace.Between San Gregorio and Point Ano Nuevo the entire fault zone is 2.5–3.0 km wide and has three primary traces or zones of faulting consisting of numerous en-echelon and anastomozing secondary fault traces. Lateral discontinuities and variable deformation of well-preserved marine terrace sequences help define major structural blocks and document differential motions in this area and south to Santa Cruz. Vertical displacement occurs on all of the fault traces, but is small compared to horizontal displacement. Some blocks within the fault zone are intensely faulted and steeply tilted. One major block 0.8 km wide east of Point Ano Nuevo is downdropped as much as 20 m between two primary traces to form a graben presently filling with Holocene deposits. Where exposed in the sea cliff, these deposits are folded into a vertical attitude adjacent to the fault plane forming the south-west margin of the graben. Near Point Ano Nuevo sedimentary deposits and fault rubble beneath a secondary high-angle reverse fault record three and possibly six distinct offset events in the past 125 ka.The three primary fault traces offset in a right-lateral sense the shoreline angles of the two lowest terraces east of Point Ano Nuevo. The rates of displacement on the three traces are similar. The average rate of horizontal offset across the entire zone is between 0.63 and 1.30 cm/yr, based on an amino-acid age estimate of 125 ka for the first terrace, and a reasonable guess of 200–400 ka for the second terrace. Rates of this magnitude make up a significant part of the deficit between long-term relative plate motions (estimated by others to be about 6 cm/yr) and present displacement rates along other parts of the San Andreas fault system (about 3.2 cm/yr).Northwestward tilt and convergence of six marine terraces northeast of Ano Nuevo (southwest side of the fault zone) indicate continuous gentle warping associated with right-lateral displacement since early or middle Pleistocene time. Minimum local crustal shortening of this block parallel to the fault is 0.2% based on tilt of the highest terrace. Five major, evenly spaced terraces southeast of Ano Nuevo on the southwest flank of Mt. Ben Lomond (northeast side of the fault zone) rise to an elevation of 240 m, indicating relatively constant uplift (about 0.19 m/ka and southwestward tilt since Early or Middle Pleistocene time (Bradley and Griggs, 1976).     

汶川地震地表破裂影响带调查与建筑场地避让宽度探讨

5.12汶川Ms8.0级地震沿龙门山中央断裂带形成长度约270km的地表破裂带,破裂带垂直和水平位移一般为1.0～5.0m,最大可达9.8m。在地表破裂带附近,建筑物破坏严重。笔者系统调查了龙门山中央断裂带地表破裂的垂直和水平位移以及地震地表破裂影响带宽度,并采用物探测试方法对部分影响带宽度进行了验证。统计结果表明,汶川地震地表破裂影响带宽度主要集中在16～60m,影响带宽度(D)与垂直位移(H)具有较好的线性关系,即D=10.11H+16.0。对于逆冲性质为主的地震地表破裂而言,上盘影响带宽度与下盘的比值一般为3:1～2:1,据此可确定地表破裂带上、下盘的避让带宽度。笔者根据现场调查并借鉴国外经验提出,上盘避让宽度下限一般不应低于15m,下盘避让宽度下限不应低于10m。本项研究对于汶川地震灾后重建场地选址具有重要的实际意义。     

卸荷条件下三峡地下厂房大型联合块体稳定性的三维数值模拟分析

块体稳定性分析一般采用只考虑重力条件下的刚体极限平衡方法来进行计算,而没有考虑开挖卸荷后块体的二次应力场对块体的稳定性的影响。文中按照实际施工工序,对三峡地下电站主厂房的两大型顶拱边墙联合块体进行三维数值模拟分析。分析结果表明:块体的顶拱部分在开挖过程中垂直厂房轴线的水平方向始终为受压状态且压应力随开挖过程逐渐增大(其很难沿结构面“爬坡”失稳,因此对结构面的起伏度进行了研究,并统计确定了其在结构面强度参数中的贡献),而垂直应力在顶拱开挖结束时卸荷基本结束,变形相对较小,沿滑面向开挖区滑移;块体的边墙部分在两个方向均表现为卸荷,特别是垂直厂房轴线的水平方向卸荷明显,在其表部甚至出现拉应力区,变形以向开挖区水平变形为主,水平方向变形量为竖向变形量的7～9倍,且总变形量较顶拱部分大得多,因此块体边墙部分在失稳前并非沿块体滑面滑移,而是向开挖区水平卸荷回弹为主。基于数值模拟结果,对块体的可能失稳的变形规律和应力分布特征进行了分析,并且提出了块体稳定度的概念,从而对其稳定性作出相应的评价。     

Structure and late quaternary activity of the northern Owens valley fault zone, Owens valley, California

The Fish Springs fault is a primary strand in the northern end of the Owens Valley fault zone (OVFZ). The Fish Springs fault is the northwest strand in a 3-km-wide left echelon step of the OVFZ which bounds the Poverty Hills bedrock high. The Fish Springs fault strikes approximately north-south, dips steeply to the east, and is marked by a prominent east-facing scarp. No other faults in the OVFZ have prominent east-facing scarps at the latitude of Fish Springs, which indicates that the Fish Springs fault has accommodated virtually all of the local late Quaternary vertical displacement on the OVFZ.

The Fish Springs fault exhibits normal dip slip with no measurable lateral slip. Vertical displacements of a Late Pleistocene (0.314 ± 0.036 Ma, 2σ) cinder cone and of an overlying Tahoe-age (0.065–0.195 m.y.) alluvial fan are 76±8 m and 31±3 m, respectively. The maximum vertical 3.3. m. Two nearly equal vertical displacements of the active stream channel in the Tioga-age fan total 2.2. m. Vertical displacement of a stream terrace incised into the cinder cone is 1.2 ± 0.3 m. The minute amount of incision into that terrace indicates that uplift of the terrace probably occurred during the 1872 Owens Valley earthquake.

Three displacements of 1.1 ± 0.2 m each apparently have occurred at the Tioga-age fan since the midpoint of the Tioga interval, allowing an average recurrence interval of 3500 to 9000 years. Based on the age and displacement of the cinder cone, the average late Quaternary vertical displacement rate is 0.24 ± 0.04 mm/yr (2σ). At this rate, and assuming an average vertical displacement of 1.1 ± 0.2 m per event, the average recurrence interval would be 4600 ± 1100 years (2σ). The recurrence interval for the Fish Springs fault is similar to that for a strand in the southern part of the OVFZ which also ruptured in 1872.

Right-lateral, normal oblique slip characterizes the OVFZ. The location of the Poverty Hills bedrock high at a left step in the north-northwest-striking fault zone is consistent with the style of slip of the zone. The pure normal slip on the north-striking Fish Springs fault and the alignment of local cinder cones along north-striking normal faults indicate that the late Quaternary maximum horizontal compression has been oriented north-south at the north end of the OVFZ. Data from southern Owens Valley indicate a similar stress regime there. Late Quaternary slip on the OVFZ is consistent with north-south maximum horizontal compression.     

The Erzincan earthquake of 13 March 1992 in Eastern Turkey: tectonic aspects

The tectonic significance of the Erzincan earthquake of 13 March, 1992 in Eastern Turkey is discussed. The intersection of the North Anatolian and The East Anatolian strike-slip fault zones has resulted in formation of the Erzincan pull-apart basin and new seismically active fault branches on its northeastern side. Local concentrations of surface ruptures strike along the most active branches of the North Anatolian fault zone (N300W) for 62 km. They are usually open fractures with northeastern sides uplifted up to 20 cm and rarely with dextral offset up to 10 cm. These secondary ruptures manifest indirectly oblique seismic fault displacement corresponding to the Late Quaternary motion on the fault zone, although at the surface the dextral component has been suppressed relative to the vertical one.     

深圳横岗-罗湖断裂中南段活动特征及现今构造变形监测

横岗-罗湖断裂是深圳断裂带的主干断裂,控制着深圳地区的地震构造环境。采用多种手段、方法对该断裂第四纪以来的活动性及现今构造变形进行研究十分重要。作者通过野外地质地貌调查、组合探槽开挖、断层带物质年龄测试(TL、ESR)等手段,分析了横岗-罗湖中南段第四纪活动期次、活动时代。初步认为,横岗-罗湖断裂在第四纪至少经历了4期构造活动,其最新活动时代在第四纪中更新世晚期,约0.14~0.31 Ma。为了定量监测该断裂现今构造变形量及变形速率,对断裂进行了动态形变监测、GPS形变监测、地应力及应变监测。监测数据表明,断裂现今变形速率在0.05~0.5 mm/a之间,属于中等偏下活动水平。断层活动方式以右旋正断与左旋逆冲交替进行,逆冲活动幅度较大,左旋活动略具优势,表明断裂现今变形具有螺旋式渐进的特征。同时,在监测时间段内,2010年11月19日深圳发生了MS2.8地震。通过分析应变仪和砂土应力仪记录的数据,发现在深圳MS2.8地震前后存在明显异常,这可能为地震前兆监测提供有效方法。     

典型红层滑坡滑带土自愈合效应试验研究

在滑坡稳定性分析和设计计算中往往选用滑带土的残余强度值,但许多研究发现滑带土在稳定期会有自愈合现象发生,表现为抗剪强度的提高。对于以蠕滑为主的红层滑坡,自愈合恢复值应该在滑坡稳定性评价中予以考虑。通过对典型红层滑坡滑带土样进行“剪切―保持―剪切”试验,研究处于残余状态下的剪切面在不同法向应力、不同保持时间下的愈合情况,并进行相应的分析与讨论。试验结果表明：（1）残余状态下的土样在保持一定时间后再次剪切出现明显峰值,证明了剪切面自愈合效应存在,但是继续剪切时恢复的强度随位移快速消失;（2）随着保持时间的增长,剪切面的强度恢复值越来越大;（3）剪切面的自愈合相比法向应力更依赖于保持时间。将得到的摩擦系数值运用断层强度恢复经验公式拟合,提出不同法向应力下常数A的取值,可在滑坡安全系数计算中参考。