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21.
掺入矿渣的水泥土强度模型试验研究及其配方优化 总被引:1,自引:0,他引:1
选取深港西部通道深圳侧接线工程范围内有代表性的淤泥土样,采用均匀设计U20(52×4)安排室内试验,建立了掺入矿渣水泥土的抗压强度回归模型;分析了混合固化剂掺入比、矿渣占固化剂的质量比和龄期及其交互作用对抗压强度的影响;模型预测值和室内平行试验的对比分析表明:该模型具有一定的可信度。模型表明矿渣占混合固化剂的质量比在一定区间内(40%~70%)对水泥土强度的增强效果显著,这与工程实践相吻合;为确定优化配比,建立了求解用多目标优化函数。考虑到现场条件与室内试验的差别,建立了12组相同配比的室内试块及现场搅拌桩对比试验,结果表明:现场搅拌桩的水泥土无侧限强度远低于室内水泥土试块强度,矿渣的增强作用与室内试验各龄期基本一致。 相似文献
22.
A numerical study on 2-D compressive wave propagation in rock masses with a set of joints along the radial direction normal to the joints 总被引:1,自引:0,他引:1
An explosion in a borehole or an accidental explosion in a tunnel will generate a two-dimensional (2-D) compressive wave that travels through the surrounding rock mass. For the problem of 2-D compressive wave propagation in a rock mass with parallel joints in the radial direction normal to the joints, parametric studies on the transmission ratio and the maximum rebound ratio are performed in universal distinct element code. The variation of the transmission ratio with the ratio of joint spacing to wavelength is generalized into a characteristic curve, which can be used as a prediction model for estimating the transmission ratio. The relationship between the maximum rebound ratio and the influence factors is obtained in charts. The charts can be used as a prediction model for estimating the maximum rebound ratio. The proposed prediction models for estimating the transmission ratio and the maximum rebound ratio are applied to a field explosion test, Mandai test in Singapore. The minimum possible values of peak particle velocity (PPV) at the monitoring points are estimated by using the proposed prediction model for estimating the transmission ratio along the radial direction normal to the joints. On the other hand, the maximum possible values of PPV are estimated by using the proposed prediction model for estimating the maximum rebound ratio along the same radial direction. The comparison shows a good agreement between the field-recorded PPVs and the estimated range of PPVs given by the minimum possible PPVs and the maximum possible PPVs at the monitoring points in Mandai test. The good agreement between the estimated and field-recorded values validates the proposed prediction models for estimating peak particle velocity in a rock mass with a set of joints due to application of a compressive wave at the boundary of a tunnel or a borehole. 相似文献
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Based on the compressive sensing,a novel algorithm is proposed to solve reconstruction problem under sparsity assumptions.Instead of estimating the reconstructed data through minimizing the objective function,the authors parameterize the problem as a linear combination of few elementary thresholding functions,which can be solved by calculating the linear weighting coefficients.It is to update the thresholding functions during the process of iteration.The advantage of this method is that the optimization problem only needs to be solved by calculating linear coefficients for each time.With the elementary thresholding functions satisfying certain constraints,a global convergence of the iterative algorithm is guaranteed.The synthetic and the field data results prove the effectiveness of the proposed algorithm. 相似文献
25.
以皖南地区某强烈变形的强风化千枚质板岩边坡为例,通过对其工程地质条件的调查,结合边坡岩体结构类型和结构面组合特征,对其变形破坏特征及稳定性进行了分析和评价。研究结果表明,边坡的变形受坡内软弱岩体(挤压破碎带)控制,剪应力的集中易使坡体产生圆弧形滑动,据此定量评价边坡的稳定性,提出合理的支护方案,减小地质灾害发生的可能。 相似文献
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伊春东风经营所新元古代花岗质片麻岩U-Pb年代学和地球化学特征 总被引:1,自引:0,他引:1
张广才岭中段东风经营所一带发现新元古代花岗质片麻岩,岩石具有高硅、富碱和低钙、镁及偏铝质-过铝质特点,稀土元素配分模式中轻稀土元素富集且缓向右倾斜,重稀土元素曲线较为平坦,为具有铕亏损的海鸥型,富集高场强元素Th、Zr、Hf,亏损Ba、Sr、P、Ti、Nb、Ta等大离子亲石元素,微量元素特征指示其形成于大陆地壳的部分熔融。锆石LA--ICP MS U--Pb定年结果表明,岩石加权平均年龄为(850.2±2.0)Ma,形成于新元古代。构造环境显示研究区花岗质片麻岩形成于挤压造山环境,为造山期的深熔产物。新元古代花岗质片麻岩的发现,表明研究区之前存在一古老的微陆块。 相似文献
28.
软岩三轴加-卸载试验的破坏特征及抗压强度取值方法研究 总被引:1,自引:0,他引:1
软岩三轴加、卸载试验中的抗压强度参数取值是一个非常关键的问题,目前还没有比较确定的方法,通常根据经验或工程要求确定。基于此,结合一组砂质泥岩的三轴加、卸载试验进行了详细研究,试验结果表明:(1)当围压大于10 MPa时,不论是三轴加载试验还是卸载试验,砂质泥岩均表现出明显的应变硬化特性;(2)砂质泥岩在三轴压缩和三轴卸荷两种应力路径的力学响应差别明显,在卸荷条件下通常只存在一条完整的剪切破坏面,而压缩条件下岩样没有明显的控制破裂面,并且剪胀效应明显;(3)将半对数法引入到软岩三轴加、卸载试验数据分析中,可以比较方便地确定软岩三轴加、卸载试验的抗压强度;(4)基于三轴加、卸载试验过程中的应力、应变增量分析,将软岩变形破坏过程分为3个阶段:平滑阶段、规则跳跃阶段和急剧跳跃阶段,各阶段划分的意义明确,可以作为抗压强度确定时的重要参考,因此,在软岩三轴试验数据分析时,可以综合采用这两种方法。研究提出的抗压强度确定方法可操作性强,在其他软岩三轴试验数据分析中值得参考借鉴。 相似文献
29.
Mohamad Tarmizi Mohamad ZULKIFLEY Tham Fatt NG John Kuna RAJ Roslan HASHIM Muhammad Aqeel ASHRAF 《《地质学报》英文版》2014,88(3):894-914
Field surveys indicate lateral variation in peat humification levels (von Post) in dominantly occurring fibric,fibric to hemic,sapric and hemie to sapric peats across a gradient from the margin towards the centre of tropical lowland peat domes.Cement-peat stabilisation can be enhanced by adding mineral soil fillers (silt,clays and fine sands) obtained from Quaternary floodplain deposits and residual soil (weathered schist).The unconfined compressive strength (UCS) of the stabilised cement-mineral soil fifler-peat mix increases with the increased addition of selected mineral soil filler.Lateral variation in the stabilised peat strength (UCS) in the top 0 to 0.5 m layer was found from the margin towards the centre of the tropical lowland peat dome.The variations in the UCS of stabilised tropical lowland peats along a gradient from the periphery towards the centre of the peat dome are most likely caused by a combination of factors due to variations in the mineral soil or ash content of the peat and horizontal zonation or lateral variation in the dominant species of the plant assemblages (due to successive vegetation zonation of the peat swamp forest from the periphery towards the centre of the tropical lowland peat dome). 相似文献