Three Dimensional Numerical Investigation of the Influence of Basement Excavation on Underlying Tunnels

Rapid urban development in cities often requires construction activities close to existing tunnels, including basement excavation directly above the tunnels. Based on three dimensional finite element method, the influence of basement excavation on the underlying tunnels was studied. In the numerical model, A tunnel was located under a rectangular excavation with its axes parallel to the long side of the rectangle. The results of numerical analyses indicate that for the tunnel located underneath the centerline of the excavation, overlying excavation will cause the shortening of horizontal diameter and the lengthening of vertical diameter of the tunnel lining. For the tunnel located close to the diaphragm wall, maximum diameter changes often take place in a sub-vertical direction due to the rotation of the tunnel lining during excavation. The spatial effect of the excavation also has an obvious influence on the displacement and distortion of the tunnel cross section.     

《饲料学》课程思政元素挖掘与实践

为改善《饲料学》课程的教学效果,从教学内容和教学方式方面进行深入改革,将课程思政元素深度融入《饲料学》课程的教学过程中。在教学过程中,将案例式教学、研讨式教学、情境式教学和参与式教学等教学方式引入课堂教学,并结合《饲料学》课程性质,深度挖掘课程思政元素并将其融入教学环节,做到润物细无声,提升学生的专业知识水平、综合素养和能力和思想政治素养。     

Safety Assessment of Circular Arches Tunnel Evacuation on Surrounding Geotechnical Environment

Based on the stochastic medium theory, influence on the surrounding rock and soil by tunnel excavation was studied. formula for predicting movement and deformation of rock and soil mass caused by tunnelling were deduced. And especially for the tunnel with circular arch section, half analytic solution for this problem was put forward. Furthermore, a program was developed to compute the movement and deformation of the rock and soil mass resulted from excavation. The deformation failure criterion of stochastic medium for estimating the surroundings safety was provided and was applied in an engineering example, which proved that the results of the research were reasonable and significant for the tunnel safety construction.     

Experimental Analysis of Construction Time Space Effect for Large Span and Flat Multi Arch Tunnel

For the large span and flat, together with the interaction effect of construction and disturbance of surrounding rock, the mechanical of large span and flat multi arch tunnel is very complicated, and the time space effect is different from that of two lane multi arch tunnel or separated tunnel. Adopting the “CTSSSRH”, the 3 D dynamic process of the tunnel construction was simulated. Analyzing the rule of surrounding rock displacement and stress with excavation, the time space effect of large span and flat multi arch tunnel was proposed.     

复合土钉在深基坑支护中的应用研究

结合唐山市第三空间综合体深基坑工程,基于FLAC3D 软件的弹塑性有限差分分析,对基坑坡顶水平位移实测数据与数值模拟结果进行了对比分析.研究表明:土钉和预应力锚索相结合的复合土钉支护方法,能够较好地控制基坑变形的发展.该工程的成功实施,对今后类似工程具有较大的借鉴价值.     

乱采滥挖野生药用植物对甘南草原生态环境的破坏

在实地考察和调查统计基础上,从甘南野生药用植物乱采滥挖时的表现,以及采挖野生药用植物造成草原植被破坏、水源涵养功能下降、药用植物资源可持续利用破坏和阻碍地方经济发展四方面,综合分析了乱采滥挖野生药用植物对甘南草原生态环境的破坏。提出运用经济和法律等手段,对甘南野生药用植物资源应进行适时、适地、留种和保护利用的原则,以遏制乱采滥挖现象,实现甘南草原野生药用植物资源的可持续利用。     

乐昌峡水利枢纽工程右岸坝肩边坡变形稳定分析

乐昌峡水利枢纽右岸高边坡风化层深厚,岩石强度弱,大坝右岸坝肩开挖后,将形成约215m的开挖边坡,边坡处于降雨强度大的地区,在施工期边坡开挖过程中的变形稳定,直接影响到碾压混凝土大坝的施工工期,十分关键.为了验算边坡开挖中和开挖后的稳定性,首先采用有限元法,对边坡开挖过程进行模拟,给出边坡的变形、屈服区等应力应变情况,利用强度折减法得到边坡的抗滑稳定安全系数,其次,用刚体极限平衡法计算安全系数,并与有限元的计算结果进行对比分析.在缺少渗流基本资料情况下,对深厚风化层的稳定状态,在极限平衡分析中,进行受降雨影响下的敏感性分析.最后对该工程提出加强观测和排水等措施,对边坡的稳定具有指导意义.     

流固耦合作用下引洮7~#隧洞开挖过程中的数值模拟分析

以甘肃历史上最大的水利工程引洮供水工程一期总干渠7#隧洞为工程背景,在考虑应力场与渗流场耦合作用下,利用ABAQUS有限元程序,建立有限元渗流模型,对隧洞埋深在200m处的含水疏松砂岩地段的围岩开挖过程进行模拟分析,得出引洮7#隧洞在开挖过程中围岩径向变形规律与特征,径向正应力、孔隙压力分布及变化规律,为隧洞的早日贯通及正常运营提供技术支持,对保证工程安全和节省投资具有积极意义.     

Three‐dimensional scanning for measurement of bulk density in gravelly soils

The measurement of bulk density in gravelly soils (>15% soil particles >2 mm) is more time‐consuming than for other soils. The excavation method, usually employed for measurement of bulk density in gravelly soils, includes excavating a void and calculating volume of the void from the weight and density of the material (e.g. sand and plaster cast) used to fill the void. A 3‐dimensional (3D) scanning system was developed to measure the volume of the void created when using the excavation method. The 3D scanning system combined a time‐of‐flight camera (Kinect ™), the KinectFusion algorithm, MeshLab and a portable computer to produce a 3D model of the void or plaster cast. Experiments were completed at three field sites where soil gravel (>2 mm) content ranged from 35 to 71% to assess the performance of the system. The void volume measured using the 3D scanning system was highly correlated with measurements using the plaster cast method (r  = 0.99). The cumulative time taken to measure soil bulk density using 3D scanning was significantly (P  <  0.001) less than for the sand replacement at 0–10, 10–20, 20–30 and 30–40 cm depth. The faster measurement of subsurface bulk density is a significant advantage of the 3D scanning system; the time taken to measure bulk density to 40 cm in 10 cm increments using the 3D scanning system was about one‐third of the sand method.     

沂河入骆马湖河口防洪治理方案研究

河口的防洪治理，一直是个难题，针对沂河入骆马湖段存在的突出问题，通过治理措施的不断探索和研究，提出河口防洪治理的新途径，采取开挖中泓，整滩灭苇，以耕代清，填洼固堤等综合治理方案，治理效果显著，并提出了进一步治理的设想。