考虑开挖损伤的高放废物地质处置库温度-渗流-应力耦合数值模拟方法     

侯会明  胡大伟  周辉  卢景景  吕涛  张帆 《岩土力学》2020,41(3):1056-1064

高放废物地质处置库处于温度?渗流?应力（THM）多场耦合环境中,对高放废物处置库进行安全评估时,需进行多场耦合分析。然而,高放废物处置库开挖引起硐壁附近围岩应力重分布,产生损伤,导致围岩热学参数（T）、渗流参数（H）和力学参数（M）发生变化,且在空间上分布不均匀,这将会对运营期处置库THM耦合演化过程产生显著影响。通过分析高放废物处置库温度?渗流?应力三场的耦合原理和处置库围岩损伤的分布和演化规律,定义了损伤变量和损伤演化准则,并将损伤变量与热学参数、渗流参数、力学参数以及多场耦合参数（Biot系数、Biot模量和温度排水系数）建立联系,将围岩损伤与温度?渗流?应力建立联系,形成了一个弹塑性损伤温度?渗流?应力多场耦合数值模型,然后利用建立的模型对瑞士Mont Terri高放废物地质处置库围岩加热试验进行模拟,对比了模拟值和试验值,比较了考虑开挖损伤和不考虑开挖损伤对高放废物地质处置库温度?渗流?应力的影响,并分析了在多场耦合作用下开挖损伤的演化规律。  相似文献   

砂土地层泥水盾构开挖面孔隙变化特征理论研究     

毛家骅  袁大军  杨将晓  张兵 《岩土力学》2020,41(7):2283-2292

为保证开挖面的稳定,泥水盾构压力舱中的泥浆必须及时在开挖面土体表层形成泥膜,泥浆压力才能有效平衡地层中的水土压力。在考虑泥浆渗滤效应的基础上,建立了砂土地层泥水盾构开挖面泥浆恒压渗透模型,分析了渗透时间、泥浆浓度、泥浆压力和地层初始孔隙率对土体孔隙率及泥浆成膜的影响。结合刀具周期性切削作用,总结了泥浆反复渗透引起的开挖面表层土体孔隙率变化规律。基于刀盘、刀具布置形式和盾构掘进参数,分析了盾构掘进期间开挖面支护机制。结果表明：在无刀具切削作用时,泥浆渗透规律主要受到泥浆和地层特性影响;在刀具周期性切削作用下,在相同的切削深度下,刀具切削周期越短,泥膜在开挖面上越难形成;刀具较小的纵向切入速度有利于开挖面上更快形成泥膜;适当减少刀盘上同一轨迹刀具布置数量,降低盾构掘进速度和刀盘转动速度,有利于盾构掘进期间开挖面上泥膜存在面积的增大,对开挖面稳定起到积极作用。  相似文献   

海岛地区分区大风预报探讨   总被引：3，自引：2，他引：1  

王雷  王坚侃 《气象科技》2005,33(5):404-407

利用海岛自动测风站网的风力资料分析了舟山海域风力的分布特征,在此基础上有针对性地把舟山海域划分为5个海区,针对目前舟山沿海海面风力预报（公众预报）范围偏大,不能正确反映舟山海域风力局地特征的重大缺陷,提出了以分海区大风预报代替舟山沿海海面风力预报的设想和预报技术思路.预报实践表明：与目前的舟山沿海海面风力预报相比,分海区大风预报不仅更加客观合理和具有针对性,而且能够有效地解决海上安全与效益之间的矛盾,适合在海岛地区推广应用.  相似文献   

温度变化对深基坑钢管支撑温度效应影响分析     

陆善佳 《岩土工程技术》2020,(1):39-42

在基坑围护工程中,大量使用内支撑结构体系,在支撑体系中采用最多的是钢管支撑,因为其属于金属材料,温度变化对支撑结构的影响不容忽视。基于弹性热力学基本原理推导出空心圆筒热应力公式,同时考虑了围护墙的侧向水平位移,定量分析变温对基坑钢管支撑轴力影响,实测轴力值及数值解验证了计算公式的正确性。结果表明:解析解大于数值解,且解析解大于实测值,偏于保守,但差值不大可作为设计安全储备,便于工程师在今后设计过程中作为参考实例。  相似文献   

Zoned Zircon from Eclogite Lenses in Marbles from the Dabie-Sulu UHP Terrane, China： A Clear Record of Ultra-deep Subduction and Fast Exhumation   总被引：3，自引：0，他引：3  

Liu Fulai 《《地质学报》英文版》2007,81(2):204-225

Eclogite lenses in marbles from the Dabie-Sulu ultrahigh-pressure (UHP) terrane are deeply subducted meta-sedimentary rocks. Zircons in these rocks have been used to constrain the ages of prograde and UHP metamorphism during subduction, and later retrograde metamorphism during exhumation. Inherited (detrital) and metamorphic zircons were distinguished on the basis of transmitted light microscopy, cathodoluminescence (CL) imaging, trace element contents and mineral inclusions. The distribution of mineral inclusions combined with CL imaging of the metamorphic zircon make it possible to relate zircon zones (domains) to different metamorphic stages. Domain 1 consists of rounded, oblong and spindly cores with dark-luminescent images, and contains quartz eclogite facies mineral inclusion assemblages, indicating formation under high-pressure (HP) metamorphic conditions of T = 571-668℃and P = 1.7-2.02 GPa. Domain 2 always surrounds domain 1 or occurs as rounded and spindly cores with white-luminescent images. It contains coesite edogite facies mineral inclusion assemblages, indicating formation under UHP metamorphic conditions of T = 782-849℃and P > 5.5 GPa. Domain 3, with gray-luminescent images, always surrounds domain 2 and occurs as the outermost zircon rim. It is characterized by low-pressure mineral inclusion assemblages, which are related to regional amphibolite facies retrograde metamorphism of T = 600-710℃and P = 0.7-1.2 GPa. The three metamorphic zircon domains have distinct ages; sample H1 from the Dabie terrane yielded SHRIMP ages of 245±4 Ma for domain 1, 235±3 Ma for domain 2 and 215±6 Ma for domain 3, whereas sample H2 from the Sulu terrane yielded similar ages of 244±4 Ma, 233±4 Ma and 214±5 Ma for Domains 1, 2 and 3, respectively. The mean ages of these zones suggest that subduction to UHP depths took place over 10-11 Ma and exhumation of the rocks occurred over a period of 19-20 Ma. Thus, subduction from～55 km to > 160 km deep mantle depth took place at rates of approximately 9.5-10.5 km/Ma and exhumation from depths >160 km to the base of the crust at～30 km occurred at approximately 6.5 km/Ma. We propose a model for these rocks involving deep subduction of continental margin lithosphere followed by ultrafast exhumation driven by buoyancy forces after break-off of the UHP slab deep within the mantle.  相似文献   

考虑隧道降水和开挖施工过程的三维地面沉降模拟     

马新雨  王俊  周欣  张云  徐永福 《高校地质学报》2021,27(2):229-239

明挖法是隧道施工中常用的一种方法,但其降水和开挖施工不可避免地会引起周围地面沉降.为了防止隧道施工对周围环境及建筑物产生严重的不良影响,地面沉降控制是检验施工支护设计合理性的关键.隧道施工造成地面沉降的主要原因有降水、开挖和支护作业,以往研究大多集中于单一因素的影响分析,为使分析结果更接近于工程实际,需将三者综合考虑,...  相似文献   

The Thickness and Scale of Late-stage Basalts in Oceanus Procellarumtwo     

Hu Xiao-yi  Chen Yuan  Zhang Xun-yu  Li Shao-lin  Xia Xue-qi  Wu Yun-zhao 《Chinese Astronomy and Astrophysics》2019,43(1):75-92

Oceanus Procellarum, the largest lunar mare, is distributed with a large area of the late-stage (Eratosthenian) basalts. Research on the thickness, volume, and eruption flux of the late-stage basalts is essential for understanding the late thermal evolution of Oceanus Procellarum, even the Moon. The Eratosthenian basalts are rich in olivine and ilmenite, while the underlying Imbrian basalts are rich in pyroxene. Their significant spectral differences are easy to be distinguished using the hyperspectral data. We determine whether a crater has penetrated the overlying basalt layer by the data of Moon Mineralogy Mapper (M³), and estimate the thickness of Eratosthenian basalts in the Oceanus Procellarum region by using a crater excavation technique. A high-resolution thickness distribution map of the last-stage basalts within the Oceanus Procellarum has been acquired. The results show that the averaged thickness of Eratosthenian basalts in the Oceanus Procellarum region varies from (24 ± 2) m to (88 ± 2) m. Among them, the thickness of Eratosthenian basalts in the western Aristarchus is the greatest (>60 m), whereas the southernmost area of the study has a minimum thickness of about 28–31 m. The basalt thickness at the Chang’e-5 potential landing site Mons Rümker is about 31–38 m. The thickness of Eratosthenian basalts in the east of Marius is about 35–45 m, which is much smaller than the value of 100 ～ 300 m estimated by Weider et al. The total volume of Eratosthenian basalts is estimated to be ～1.39 × 10⁴ km³, which is only about 1.6% of total basalts in Oceanus Procellarum. This indicates that the magmatism in the Eratosthenian period has been greatly weakened compared to the Imbrian period.  相似文献   

Simplified method for evaluating the response of existing tunnel induced by adjacent excavation     

Guohui Feng  Changjie Xu  Luju Liang  Ming-wang Tey  Min-liang Chi  Shangqi Ge 《国际地质力学数值与分析法杂志》2023,47(1):54-81

Adjacent excavation may have a negative influence on the existing tunnel underneath. Thus, it is important to evaluate the response of the tunnel due to adjacent excavation. However, there is little report about using the Kerr foundation model to simulate the tunnel-soil interaction. Meanwhile, the Timoshenko beam, which can take the tunnel shearing effect into consideration, is more suitable to estimate the behavior of the tunnel. To simulate the interaction between soil and tunnel, the existing tunnel is simplified as a Timoshenko beam lying on the Kerr foundation model, and a simplified theoretical method is proposed to calculate the response of the existing tunnel induced by adjacent excavation. The proposed method is validated by two field case studies. Results indicate that the predictions given by the proposed method show great agreement with field measurements and it is more accurate to evaluate the tunnel-soil interaction compared with the previous method. The further parametric study shows that the relative position between excavation and tunnel, the ground Young's modulus, the depth of existing tunnel centerline, and length and width of excavation are both significant factors governing the tunnel response induced by adjacent excavation, while the influence of tunnel shear stiffness and skew between tunnel and excavation are slight. The proposed method can be applied to predict the potential risk of existing tunnels induced by adjacent excavation in relevant engineering projects.  相似文献   

A calculation method for deformation of diaphragm wall of narrow deep foundation pit in soft soil considering spatio-temporal effectEI北大核心     

张坤勇  张梦  孙斌  李福东  简永洲 《岩土力学》2023,(8):2389-2399

为准确评估软土地区基坑施工安全以及对周围环境的影响,开挖过程中的时间和空间影响因素不可忽视。以长江漫滩软土地区某深基坑开挖工程为依托,首先建立考虑顺逆结合施工过程的有限元模型,将地连墙水平位移的计算值与实测值进行对比,验证有限元计算的可靠性;基于理论分析、数值计算和实测数据,采用坑角效应影响系数和等效水平抗力系数来衡量时空效应对支护变形的影响,提出考虑时空效应的地连墙变形计算方法;通过工程实例验证了在软土地区基坑设计计算中考虑时空效应的必要性以及所提计算方法的合理性。该研究成果可为软土地区深基坑变形计算提供有益借鉴。  相似文献