基于模型试验的桩间距对组合式钢管抗滑桩抗滑效果的影响分析     

储召军  石少卿  孙建虎  李季  崔廉明 《岩土力学》2018,39(3):848-853

通过大型物理模型试验分别对3种不同桩间距组合式钢管抗滑桩治理滑坡的力学效应进行研究,对比分析桩顶位移、剪出口位移、桩身弯矩随荷载的变化规律和桩体、滑坡的破坏情况,讨论桩间距对组合式钢管抗滑桩抗滑效果的影响。试验结果表明,当桩间距由18.7 cm依次增大至23.5、28.0 cm,即由3.9d增大至4.9d、5.8d（d为小直径圆形钢管的外径）,同等荷载作用时桩顶水平位移、剪出口水平位移、桩身弯矩逐渐增大,但桩间距由3.9d增大至4.9d时,位移与弯矩的增大幅度远大于桩间距由4.9d增大至5.8d。建议在组合式钢管抗滑桩设计中,若滑坡推力较小,可适当增大桩间距至5.8d甚至更大;若滑坡推力较大,应适当减小桩间距至3.9d甚至更小。无论滑坡推力较大或者较小,桩间距为4.9d的组合式钢管抗滑桩治理滑坡的性价比均较低。  相似文献   

地面垂直钻孔预抽特厚煤层瓦斯数值试验与应用     

袁亮  刘业娇  田志超  唐春安  薛俊华  段昌瑞  张寒 《岩土力学》2019,40(1):370-378

为解决塔山煤矿高强度开采条件下瓦斯低含量、高涌出的问题,同时为了弥补大型物理实验和现场试验成本高、操作难的缺点,根据该矿8101工作面所属区域煤层的地质和瓦斯赋存条件,确定了数值试验方案,对地面垂直钻孔预抽特厚煤层瓦斯的效果进行优化分析。基于煤岩（体）的孔隙特征,构建了含瓦斯煤岩（体）破裂过程气-固耦合和渗透率-损伤耦合数学本构模型。采用RFPA2D瓦斯分析版软件建立地面钻孔抽放瓦斯的数值计算模型,设置有关简化条件、边界条件和物性参数,通过数值试验得出：地面垂直钻孔的终孔位置布置在煤层底部比较合理;在综合考虑地面垂直钻孔投入成本和瓦斯抽采效果的基础上,确定地面垂直钻孔间距为50～60 m比较合理。同时,由8101工作面地面垂直钻孔抽采煤层瓦斯的实际应用效果分析可知,当地面垂直钻孔的终孔位置布置在煤层底部,且钻孔间距布置为50 m时,能够实现良好的瓦斯抽放效果,这也从一定程度上进一步验证了数值试验的合理性和可行性。  相似文献   

复合岩层中滚刀旋转切割破岩效率试验研究     

温森  周书宇  盛桂琳 《岩土力学》2019,40(7):2628-2636

TBM掘进经常遇到复合岩层,在该地层中施工对滚刀破岩非常不利。为了提高掘进效率,降低工程造价,开展复合岩层滚刀破岩效率研究很有必要。鉴于此,采用滚刀岩机作用综合试验台对砂岩、花岗岩复合(复合比例为4(25) 6)而成的岩层进行5组刀间距下3种贯入度的3把滚刀同步旋转切割试验;试验过程中监测破岩总法向力、总扭矩,并分别收集两种岩石的岩渣进行筛分、称重;依据试验结果分析不同刀间距、贯入度下的法向力、扭矩及比能的关系。研究表明:不同刀间距时,平均法向力、平均扭矩随贯入度的增加而增大但两者的增加趋势不同,即平均法向力随着贯入度的增加几乎呈直线增大,而平均扭矩随着贯入度的增加其递增趋势减小;不同贯入度下存在不同的最优刀间距;砂岩、花岗岩切割轨迹长度比例为4:6时刀间距与贯入度的比值在14左右,破岩效率最高。  相似文献   

高密度电法反演分辨率数值模拟与分析     

孟凡松  张刚  赵卫东  陈梦君  李怀良 《物探化探计算技术》2019,(4):462-468

高密度电法在反演过程中,电极距相比电性异常体横向长度过大时,电性异常体在反演中无法得到约束;某电极距下,当电性异常体埋藏深度增加大到一定深度时,在反演中电性异常体也无法得到约束。针对以上两个问题,利用res2dmod正演软件建立模型,再利用res2dinv反演软件对模型进行反演,通过对比分析结果表明:温纳、偶极和微分三种装置分两种情况:如果电极距小于20m模拟条件下,对于埋藏深度为5m且剖面面积不同的电性异常高阻体(异常体电阻率=100Ω·m,围岩电阻率=10Ω·m),横向反演分辨率,温纳装置大于微分和偶极装置;电极距小于12.75m时,微分装置大于偶极装置,电极距大于12.75m时,偶极装置大于微分装置。如果电极距在2m^8m范围内,对于剖面面积为4×4(m2)的电性异常高阻体(异常体电阻率=100Ω·m,围岩电阻率=10Ω·m),其最大约束深度随电极距的增大而先增大后减小;相同电极距下,偶极装置的最大约束深度>微分装置的最大约束深度>温纳装置的最大约束深度。  相似文献   

60年来我国主要粮食作物适宜生长区的时空分布     

宁晓菊  张丽君  秦耀辰  刘凯 《地球科学进展》2019,(2):191-201

模拟作物适宜生长区的时空分布是分析气候变化对作物生长影响、提高作物生长适应能力的重要内容。选择影响主要粮食作物(小麦、玉米和水稻)生长的气候要素,结合地表土壤和地面高程要素与农业观测站数据,模拟和分析1953—2012年主要粮食作物适宜生长区的变动,评估气候变化下作物的适应能力。研究发现:(1)60年来3种粮食作物适宜生长区对气候变化响应程度从大到小依次是小麦、水稻和玉米。(2)同一时空尺度上,主要粮食作物适宜生长类型区在南方农区较北方农区多样化,在山地较盆地多样化,在高原较平原多样化。(3)小麦生长适应气候变化的能力在多数农区略有上升。玉米生长的适应能力在北方和南方农区分别略微提高和下降。水稻生长的适应能力在长江中下游区、西南区和华南区相对稳定,在黄淮海区和东北区分别下降和提高。(4)60年来,主要粮食作物综合生长适应气候变化的能力在黄淮海区和长江中下游区下降,在其余农区升高。(5)玉米和水稻适宜生长区分别与播种面积和作物产量显著相关,这为模拟未来不同气候情景下二者适宜生长区的分布提供了可行性。小麦适宜生长区与播种面积和产量均不显著相关,未来需要考虑更多因素精准识别小麦适宜生长区,以便更为有效地提高小麦生长对气候变化的适应能力。  相似文献   

侧限条件下加筋对土体沉降的影响     

傅志斌  刘志华  介玉新 《岩土工程技术》2019,(4):245-248,F0003

针对侧限条件下加筋对土体沉降的影响问题,开展离心模型试验,设置三组对比试验,即在试验土体中未铺设筋材、铺设竖向间距分别为5 cm和3 cm间距的筋材,记录土体中典型点沉降量。试验发现典型点沉降随加速度增加而增加,未铺设筋材、铺设5cm间距筋材及铺设3cm间距筋材的土体沉降量依次降低。表明侧限情况下加筋也能够减小土体沉降,而且加筋间距越小,控制土体沉降效果越显著。侧限情况下筋材仍能起作用可能与土体变形不均有关。这种发现有利于深入理解加筋的作用机理。  相似文献   

多节扩孔钻孔灌注桩（DX桩）土中应力场的变化规律     

李光茂 《上海国土资源》2001,51(1):33-37

本文运用有限元法计算分析研究了多节扩孔钻孔灌注桩（DX桩）不同支盘数和支盘间距时土中应力场及其工作性状的变化规律，并从应力角度探讨了该桩对沉降的控制作用。  相似文献   

Noble gases in a section across the vapor dominated geothermal field of Larderello,Italy     

Emanuel Mazor 《Pure and Applied Geophysics》1978,117(1-2):262-275

Noble gases were studied in six wells, located on a 4.5 km south to north section across the Larderello field. Depth of wells, flow and gas/steam ratios are known to increase from south to north. Exploitation progressed in the same direction. The following noble gas patterns are observable: (a) Atmospheric Ar, Kr and Xe reflect productions of gas-depleted water at Colombaia 2 and progressively more gas-enriched steam towards the Gabbro wells. (b) Radiogenic⁴He and⁴⁰Ar are observed in increasing concentrations from south to north. (c) The radiogenic and atmospheric gases reveal a positive correlation, indicating that the recharging water enters deep into the system, and gets well mixed with the radiogenic gases prior to the steam separation. (d) Gas contents and relative abundances of radiogenic argon decrease with production, thus supplying markers for the degree of exploitation in a well and a guide for optimum well spacing. (e) Excess neon over argon is observed and discussed in terms of crustal origin versus possible fractionation of atmospheric noble gases due to pertial steam separation.  相似文献   

Single beam analogy for describing soil–pile group interaction     

Kazuo Konagai  Yuanbiao Yin  Yoshitaka Murono   《Soil Dynamics and Earthquake Engineering》2003,23(3):31-39

Most laterally loaded piles are flexible in the sense that they are not deformed over their entire lengths. Instead, pile deflections become negligible below an ‘active pile length’ L_a. This L_a is an important parameter that governs the overall behavior of a rigidly capped pile group. In the present approach, piles closely grouped together beneath a superstructure are viewed as a single equivalent upright beam whose stiffness matrix determines L_a. This idea is verified for different cases of pile spacing, and is further extended for nonlinear behavior of soils surrounding grouped piles.  相似文献   

Drillability prediction: geological influences in hard rock drill and blast tunnelling     

K. Thuro 《International Journal of Earth Sciences》1997,86(2):426-438

 Usually the main subject in preliminary site investigations prior to tunnelling projects is the prediction of tunnel stability. During the past years in conventional drill and blast tunnelling, problems have occurred also connected to the accurate prediction of drillability in hard rock. The drillability is not only decisive for the wear of tools and equipment but is – along with the drilling velocity – a standard factor for the progress of excavation works. The estimation of drillability in predicted rock conditions might bear an extensive risk of costs. Therefore, an improved prediction of drilling velocity and bit wear would be desireable. The drillability of a rock mass is determined by various geological and mechanical parameters. In this report some major correlations of specific rock properties and especially geological factors with measured bit wear and drilling velocity are shown. Drilling velocity is dependent on a lot of geological parameters: Those principal parameters include jointing of rock mass, orientation of schistosity (rock anisotropy), degree of interlocking of microstructures, porosity and quality of cementation of clastic rock, degree of hydrothermal decomposition and weathering of a rock mass. Drilling bit wear increases with the equivalent quartz content. The equivalent quartz content builds the main property for the content of wear-relevant minerals. For various groups of rock types different connections with the equivalent quartz content could be detected. In sandstone bit wear is also dependent on porosity or the quality of the cementation. Finally, an investigation program is submitted, which helps to improve the estimation of rock drillability in planning future tunnel projects. Received: 14 June 1996/Accepted: 10 January 1997  相似文献