预应力锚固技术在桥台加固中的应用

预应力锚固技术由于其高效、经济的特点,近年来在各类岩土加固工程中得到了广泛的应用,高家庄2号桥台加固采用了对穿预应力钢筋加固技术,在加固工程施工过程中,为了保持桥台的稳定采取了临时加固措施,通过对这一工程实践特点的分析和论述,在施工程序和方法方面进行了探讨和总结。     

Comparative study procedure for the safety evaluation of high arch dams

A set of factors for the safety evaluation of the dam heel crack and ultimate bearing capacity of high arch dams is presented: the curtain safety factor k₁, the structural mutation safety factor k₂, and the ultimate safety factor k₃. The factor k₁ reflects the curtain safety at the dam heel, k₂ describes the structural mutation stage for the adjustment of the multiple arch–cantilever system, and k₃ reflects the ultimate bearing capacity of the entire dam structure. A comparative study on the performance and ultimate bearing capacity of dams is performed to give a more reasonable evaluation criterion of safety factors.     

基于统一强度理论抗滑桩桩间距的计算

在已有抗滑桩桩间距研究的基础上,对桩间土拱进行受力分析.从侧阻力条件和土拱强度条件两个方面对抗滑桩桩间距进行了计算,将统一强度理论引入土拱强度的分析,藉此分别判断拱顶前缘、后缘及拱脚处土体是否处于临界状态,可得3个桩间距值,取相应的最小桩间距作为设计桩间距.此方法对于滑坡推力的矩形、三角形和梯形分布形式均适用,并可考虑...     

对巷道开孔卸载参数的研究

本文论述了巷道开孔应力卸载的实质，以轴变论和开孔卸载后使巷道围岩达到较好的受力状态出发点，初步提出了确定开孔卸载参数的方法，并通过有限元数值计算，验证了这一方法。     

钢管-钢管混凝土复合拱桥动力特性分析

福建省福鼎市山前大桥是一座应用钢管－钢管混凝土复合拱桥概念设计成的试验桥，本文以它作为研究对象，进行了动力特性的测试和计算，并讨论了主要结构参数对其动力特性的影响，为此类桥梁的设计提供参考。     

渤海海域沙垒田凸起西北部奥陶系碳酸盐岩储层发育主控因素与分布预测

基于岩心、薄片观察以及同位素、稀土元素等分析资料,明确了渤海海域沙垒田凸起西北部奥陶系碳酸盐岩潜山储层岩性主要为白云岩,储集空间包括溶蚀孔、洞、缝,储层类型为裂缝-孔隙型,裂缝是沟通孔洞的重要通道。储层演化机制上,碳酸盐岩白云石化作用、岩溶作用和构造作用是储层发育的主控因素:白云石化作用是储层发育的基础,岩溶作用是储层发育的重要保障,构造作用是储层发育的关键。地震地质储层综合预测表明研究区西南部为风化壳岩溶储层发育的有利地区。     

Mechanism and countermeasures of preceding tunnel distortion induced by succeeding EPBS tunnelling in close proximity

Twin tunnels are frequently used to address the increasing transportation demands in large cities. To ensure the safety of twin tunnels in close proximity, it is often necessary to take protective measures that have not been well studied. Field monitoring was conducted for a project of twin earth pressure balance shield (EPBS) tunnels in typical soft ground. The preceding tunnel was reinforced by various measures, including trailer bracing, compensation grouting, artificial freezing and scaffold bracing. The entire deformation of the reinforced tunnel was recorded during the succeeding tunnelling process. A three dimensional finite-element method (FEM) model was established to simulate the entire process of twin EPBS tunnelling, particularly the reinforcement measures. The computed deformations of the reinforced tunnel were consistent with the measured data. Furthermore, the stress history and pore pressure of the surrounding soil were analysed to investigate the deformation mechanism of the tunnel. Both the measured and computed results indicate that although the face pressure of the succeeding tunnel was smaller than the earth pressure at rest, the preceding tunnel could still experience an inward horizontal convergence and a deflection away from the succeeding tunnel. These distortion modes were caused by the squeezing effect of the horizontal soil arch in front of the succeeding tunnel face. Finally, convergence and deflection indices were proposed to quantify and assess the effectiveness of the reinforcement measures. The trailer bracing, as an “in-tunnel” reinforcement technique, was found to be the most effective method for controlling tunnel convergence. However, artificial freezing as an “out-tunnel” reinforcement technique led to the largest reductions in tunnel deflection. A combination of both “in-tunnel” and “out-tunnel” reinforcements was recommended.     

整体桥高性能混凝土桩−土相互作用试验研究

高性能混凝土（高性能复合水泥基材料engineered cementitious composite,简称ECC与超高性能混凝土ultra-high performance concrete pile,简称UHPC）桩基具有良好的抗开裂性能和较高的承载能力,能较好地满足整体桥纵桥向变形。开展了砂土中高性能混凝土桩低周往复拟静力试验,得到了桩基的破坏特点、抗开裂能力以及极限承载力,分析了其桩身变形、桩侧土抗力以及桩身应变等分布规律,并与钢筋混凝土（RC）桩进行了比较。在此基础上,讨论了几种常用规范的适用性。试验结果表明,ECC、UHPC材料能有效减轻桩基的破坏程度、提高桩基的抗开裂能力以及水平承载力;相比RC桩基,高性能混凝土桩基的破坏位置更深,桩基的有效桩长更大,抗震性能更好;其中,ECC桩基的抗开裂能力最强,开裂荷载可达5.8 kN,开裂位移可达15 mm。试验结果还表明,高性能混凝土桩基的变形沿埋深方向不断的减小,埋深1.5 m以下位置基本为0;桩侧土抗力先增大后减小,桩底土抗力和变形量为0;桩身应变分布较为对称,且呈“橄榄”形,在埋深4D～6D（D为桩径）区间内桩身应变较大。分析计算表明,当桩顶位移在10 mm以内时,“m”法与API新规范法均能较好地计算高性能混凝土桩的桩身变形;当位移超过10 mm后,“m”法与实际数值相差较大。“m”法与API新规范法均不能较好地计算桩身弯矩,适用性不高;桩侧土抗力建议采用API新规范法。     

基于相对变形方法的桩后土拱模型试验研究

为分析桩后土拱在滑动过程中的动态演化过程,设计了一种新型的土体相对变形监测系统,开展了物理模型试验和滑体强度参数分析试验,基于试验监测数据,引入了两个无量纲参数表征滑体相对变形程度和不均匀变形程度。试验结果表明：（1）基于桩后土拱变形与传递侧向力曲线特征,土拱演化可分为弹性形成阶段、塑性发展阶段和破坏阶段3个阶段。在破坏阶段观察到显著的三维破坏特征,在水平面上,土拱表现出成层的拱圈挤出破坏;在竖直面上,表现出中下部的滑体土率先开裂并塌落,然后在顶部出现悬链形状的裂缝。（2）随相对变形变化,桩后滑体强度参数在滑动过程中是处于一个动态的强化过程,就强化程度而言,黏聚力较内摩擦角更敏感。（3）前期相对靠后的滑体的相对变形程度与参数强化程度分别高于相对靠前的滑体和桩间滑体,因此,桩周滑体裂缝在向后发展过程中逐渐向桩间中心线发生偏转,在裂缝贯通后形成稳定支撑的拱形结构。     

Study on Structure of Arched Longitudinal Beams of Deep-Water Wharf

High-pile and beam-slab quays have been widely used after several years development.They are mature enough to be one of the most important structural types of wharves in China coastal areas. In order to accommodate large tonnage vessels, wharves should be constructed in deep water gradually. However, conventional high-pileand beam-slab structures are hard to meet the requirements of large deep-water wharf.According to arch''s stresscharacteristics, a new type of wharf with catenary arched longitudinal beams is presented in this paper. The new wharf structure can make full use of arch''s overhead crossing and reinforced concrete compression resistance, improve the interval between transverse bents greatly, and decrease underwater construction quantity. Thus, the construction cost cab be reduced. Take the third phase project of the Yangshan Deep-water Port for example, comparative analysis on catenary arched longitudinal beams and conventional longitudinal beams has been made. The result shows that with the same wharf length and width, the same loads and same longitudinal beam moment, catenary arch structure can improve the interval between bents up to 28 m, decrease the number of piles and underwater construction quantity.