沙坝泄洪洞沉降的可靠性分析
发布时间：2018-08-18 13:12
【摘要】：为解决陕北风沙区水资源短缺的问题，利用当地材料在河流上筑坝蓄水，修建水利工程的举措得到了实施。然而目前在风沙区修建水工建筑物的实践和研究并不多，水工建筑物修建后往往出现诸多未预料的问题。针对该地区已建水工建筑物所出现的问题开展研究，不仅能为建筑物的安全加固提供科学依据，而且还可以为修建类似工程提供一定的借鉴。 本文首先采用单元“生死”技术和分级加载的方法模拟某水库泄洪洞及沙坝的修筑过程，计算施工期泄洪洞的沉降值；其次，对蓄水期不同工况下泄洪洞的沉降进行仿真模拟，并将计算得到的沉降值与实测值进行比较，，验证数值模型的正确性；最后采用ANSYS软件的PDS模块对正常蓄水位工况下泄洪洞的沉降进行可靠性分析研究。得到泄洪洞沉降的相关规律如下： （1）施工期采用分级加载计算，随着上部坝体的填筑，泄洪洞的沉降量逐步增大，模拟得到洞体最大沉降值为24.35cm，出现在坝轴线附近，远离坝轴线处沉降量逐渐减小，在泄洪洞上游段接缝处产生了明显的不均匀沉降。 （2）水库蓄水到1064.00m高程时，模拟得到泄洪洞最大沉降量为24.34cm，沉降曲线与竣工期沉降曲线几乎完全重合；蓄水到1082.00m高程时，模拟得到泄洪洞最大沉降量为25.10cm，沉降曲线在坝轴线附近及下游部分几乎与第六次和第七次加载得到的泄洪洞沉降曲线完全重合，而上游部分则沉降很大，与前两次加载所得到的沉降结果差异明显。 （3）水库蓄水到1064.00m高程时，泄洪洞沉降的模拟计算值与实际观测值比较接近，两条沉降曲线走势一致，在泄洪洞的两端沉降比较小，两条沉降曲线几乎重合，中间部分沉降较大，两条沉降曲线出现一定的偏离，泄洪洞沉降的模拟值比实际观测值略大一些。模拟计算和实际观测得到的最大沉降值均在同一观测点出现，沉降模拟结果与实际工程沉降观测结果基本相符，沉降规律一致。 （4）对数值模型进行1000次蒙特卡罗模拟分析，得到正常蓄水位工况下泄洪洞最大沉降量的平均值、最大值和最小值分别为25.36cm、35.02cm和19.59cm；在置信度为95%情况下，最大沉降量主要分布在22-30cm之间。 （5）在显著性水平为2.5%情况下，坝体基础密实沙层的压缩模量对泄洪洞最大沉降量的影响最为显著，灵敏系数为0.787，在总影响因素中占45.81%；其次是坝体材料的密度和坝体基础松散沙层的压缩模量，灵敏系数分别为-0.507和0.255，在总影响因素中分别占29.51%和14.84%；其他几个因素对泄洪洞最大沉降量的影响并不显著。 （6）采取工程措施增大坝体基础的压缩模量，可以明显抑制泄洪洞的沉降，是防止泄洪洞继续沉降的最有效和可行的方法。
[Abstract]:In order to solve the problem of water resources shortage in wind-sand region of northern Shaanxi, the measures of using local materials to dam and store water on rivers and to build water conservancy projects have been carried out. However, there is not much practice and research on the construction of hydraulic structures in wind and sand areas, and many unexpected problems often occur after the construction of hydraulic structures. The research on the existing hydraulic structures in this area can not only provide a scientific basis for the safety reinforcement of the buildings, but also provide some reference for the construction of similar projects. In this paper, the element "birth and death" technique and the method of graded loading are used to simulate the construction process of a reservoir flood discharge tunnel and sand dam, and the settlement value of the flood discharge tunnel during the construction period is calculated. Secondly, the settlement of the flood discharge tunnel under different working conditions during the storage period is simulated. The calculated settlement value is compared with the measured value to verify the correctness of the numerical model. Finally, the reliability analysis of the settlement of the flood discharge tunnel under the normal storage water level condition is carried out by using the PDS module of the ANSYS software. The relative rules of settlement of flood discharge tunnel are as follows: (1) the settlement of flood discharge tunnel increases gradually with the filling of the upper dam, and the maximum settlement value of the tunnel is 24.35 cm, which appears near the dam axis during the construction period, and the settlement of the tunnel is calculated as follows: (1) with the filling of the upper dam body, the settlement of the flood discharge tunnel increases gradually during the construction period. The settlement far away from the axis of the dam gradually decreases, resulting in obvious uneven settlement at the joint of the upstream section of the flood discharge tunnel. (2) when the reservoir impounds to 1064.00 m elevation, The maximum settlement of the flood discharge tunnel is 24.34 cm, and the settlement curve is almost identical with the settlement curve in the completion period, and when the water storage reaches 1082.00 m, The maximum settlement of the flood discharge tunnel is 25.10 cm, and the settlement curve near the dam axis and downstream almost coincides with the settlement curve of the sixth and seventh loading, while the upstream part is very large. The results of settlement obtained by the first two loads are obviously different. (3) at the height of 1064.00 m, the simulated calculated value of the settlement of the flood discharge tunnel is close to the actual observed value, and the two settlement curves are in agreement with each other. The settlement at both ends of the flood discharge tunnel is relatively small, the two settlement curves almost coincide with each other, the middle part of the settlement is larger, and the two settlement curves deviate to a certain extent. The simulated settlement value of the flood discharge tunnel is slightly larger than the actual observed value. The maximum settlement values obtained by the simulation calculation and the actual observation appear at the same observation point, and the settlement simulation results are basically consistent with the actual engineering settlement observation results. The settlement law is consistent. (4) 1000 times Monte Carlo simulation analysis of the numerical model is carried out, and the average value of maximum settlement of flood discharge tunnel under normal storage water level is obtained, the maximum and minimum values are 25.36 cm, 35.02 cm and 19.59 cm respectively, and when the confidence is 95%, The maximum settlement is mainly distributed between 22-30cm. (5) at the significant level of 2.5%, the modulus of compression of the dense sand layer of the dam foundation has the most significant effect on the maximum settlement of the flood discharge tunnel, the sensitivity coefficient is 0.787, accounting for 45.81% of the total influencing factors; Secondly, the density of dam material and the compression modulus of loose sand layer of dam foundation are -0.507 and 0.255, respectively, which account for 29.51% and 14.84% of the total influencing factors respectively. The influence of other factors on the maximum settlement of flood discharge tunnel is not significant. (6) adopting engineering measures to increase the compression modulus of dam foundation can obviously restrain the settlement of flood discharge tunnel. It is the most effective and feasible method to prevent the continuous settlement of flood discharge tunnel.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV651;TV698.25
本文编号：2189572
[Abstract]:In order to solve the problem of water resources shortage in wind-sand region of northern Shaanxi, the measures of using local materials to dam and store water on rivers and to build water conservancy projects have been carried out. However, there is not much practice and research on the construction of hydraulic structures in wind and sand areas, and many unexpected problems often occur after the construction of hydraulic structures. The research on the existing hydraulic structures in this area can not only provide a scientific basis for the safety reinforcement of the buildings, but also provide some reference for the construction of similar projects. In this paper, the element "birth and death" technique and the method of graded loading are used to simulate the construction process of a reservoir flood discharge tunnel and sand dam, and the settlement value of the flood discharge tunnel during the construction period is calculated. Secondly, the settlement of the flood discharge tunnel under different working conditions during the storage period is simulated. The calculated settlement value is compared with the measured value to verify the correctness of the numerical model. Finally, the reliability analysis of the settlement of the flood discharge tunnel under the normal storage water level condition is carried out by using the PDS module of the ANSYS software. The relative rules of settlement of flood discharge tunnel are as follows: (1) the settlement of flood discharge tunnel increases gradually with the filling of the upper dam, and the maximum settlement value of the tunnel is 24.35 cm, which appears near the dam axis during the construction period, and the settlement of the tunnel is calculated as follows: (1) with the filling of the upper dam body, the settlement of the flood discharge tunnel increases gradually during the construction period. The settlement far away from the axis of the dam gradually decreases, resulting in obvious uneven settlement at the joint of the upstream section of the flood discharge tunnel. (2) when the reservoir impounds to 1064.00 m elevation, The maximum settlement of the flood discharge tunnel is 24.34 cm, and the settlement curve is almost identical with the settlement curve in the completion period, and when the water storage reaches 1082.00 m, The maximum settlement of the flood discharge tunnel is 25.10 cm, and the settlement curve near the dam axis and downstream almost coincides with the settlement curve of the sixth and seventh loading, while the upstream part is very large. The results of settlement obtained by the first two loads are obviously different. (3) at the height of 1064.00 m, the simulated calculated value of the settlement of the flood discharge tunnel is close to the actual observed value, and the two settlement curves are in agreement with each other. The settlement at both ends of the flood discharge tunnel is relatively small, the two settlement curves almost coincide with each other, the middle part of the settlement is larger, and the two settlement curves deviate to a certain extent. The simulated settlement value of the flood discharge tunnel is slightly larger than the actual observed value. The maximum settlement values obtained by the simulation calculation and the actual observation appear at the same observation point, and the settlement simulation results are basically consistent with the actual engineering settlement observation results. The settlement law is consistent. (4) 1000 times Monte Carlo simulation analysis of the numerical model is carried out, and the average value of maximum settlement of flood discharge tunnel under normal storage water level is obtained, the maximum and minimum values are 25.36 cm, 35.02 cm and 19.59 cm respectively, and when the confidence is 95%, The maximum settlement is mainly distributed between 22-30cm. (5) at the significant level of 2.5%, the modulus of compression of the dense sand layer of the dam foundation has the most significant effect on the maximum settlement of the flood discharge tunnel, the sensitivity coefficient is 0.787, accounting for 45.81% of the total influencing factors; Secondly, the density of dam material and the compression modulus of loose sand layer of dam foundation are -0.507 and 0.255, respectively, which account for 29.51% and 14.84% of the total influencing factors respectively. The influence of other factors on the maximum settlement of flood discharge tunnel is not significant. (6) adopting engineering measures to increase the compression modulus of dam foundation can obviously restrain the settlement of flood discharge tunnel. It is the most effective and feasible method to prevent the continuous settlement of flood discharge tunnel.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV651;TV698.25
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