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201.
By using small scale model tests, the interference effect on the vertical load-deformation behavior of a number of equally
spaced strip footings, placed on the surface of dry sand, was investigated. At any stage, all the footings were assumed to
(i) carry exactly equal magnitude of load, and (ii) settle to the same extent. No tilt of the footing was permitted. The effect
of clear spacing (s) among footings on the results was explored. A new experimental setup was proposed in which only one footing
needs to be employed rather than a number of footings. The bearing capacity increases continuously with decrease in spacing
among the footings. The interference effect becomes further prominent with increase in soil friction angle. In contrast to
an increase in the bearing capacity, with decrease in spacing of footings, an increase in the footing settlement associated
with the ultimate state of shear failure was observed. The present experimental observations were similar to those predicted
by the available theory, based on the method of characteristics. As compared to the theory, the present experimental data,
however, indicates much greater effect of interference especially for larger spacing among footings. 相似文献
202.
K. Vinod kumar R. C. Lakhera Tapas R. Martha R. S. Chatterjee A. Bhattacharya 《Environmental Geology》2008,55(4):789-799
Mass movements such as landslides in mountainous terrains are natural degradation processes and one of the most important
landscape-building factors. Varunawat Parbat overlooking Uttarkashi town witnessed a series of landslides on 23 September
2003 and the debris slides and rock falls continued for 2 weeks. This landslide complex was triggered due to the incessant
rainfall prior to the event, and its occurrence led to the blockage of the pilgrim route to Gangotri (source of the Ganges
river) and evacuation of thousands of people to safer places. Though there was no loss of lives due to timely evacuation,
heavy losses to the property were reported. High-resolution stereoscopic earth observation data were acquired after the incidence
to study the landslide in detail with emphasis on the cause of the landslide and mode of failure. Areas along the road and
below the Varunawat foothill region are mapped for landslide risk. It was found that the foothill region of the Varunawat
Parbat was highly disturbed by man-made activities and houses are dangerously located below steep slopes. The potential zones
for landslides along with the existing active and old landslides are mapped. These areas are critical and their treatment
with priority is required in order to minimise further landslide occurrences. 相似文献
203.
There could be some discontinuities in a soil media such as layers, earth structures, cracks, and fissures so that estimation
of stresses and deformations in these types of soil masses are somewhat different from continuous masses. The discontinuities
in a soil mass could be considered as a special link between two blocks. Transmitted swelling pressures affected by the soil
properties of the backfill especially at the interface between the backfill and retaining wall. In order to estimate the transmitted
swelling pressure distribution behind a retaining wall, using with interface element, a new finite element model and a code
(SWELPRES) have been developed. To evaluate the effect of backfill characteristics and interface element from the transmitted
lateral swelling pressures, four cases of thickness of backfills with or without interface elements are investigated. 相似文献
204.
Eduardo E. Alonso Sarah M. Springman Charles W. W. Ng 《Geotechnical and Geological Engineering》2008,26(6):817-826
Two large-scale “in situ” demonstration experiments and their instrumentation are described. The first test (FEBEX Experiment)
involves the hydration of a compacted bentonite barrier under the combined effect of an inner source of heat and an outer
water flow from the confining saturated granite rock. In the second case, the progressive de-saturation of Opalinus clay induced
by maintained ventilation of an unlined tunnel is analyzed. The paper shows the performance of different sensors (capacitive
cells, psychrometers, TDR’s) and a comparison of fill behaviour with modelling results. The long term performance of some
instruments could also be evaluated specially in the case of FEBEX test. Capacitive sensors provide relative humidity data
during long transient periods characterised by very large variations of suction within the bentonite. 相似文献
205.
岩矿显微组构对水银洞金矿成因的指示 总被引:1,自引:0,他引:1
黔西南水银洞金矿为产于上二叠统龙潭组中的超大型、高品位金矿床,矿床由多个金矿体组成.工业金矿体顺层产于龙潭组含煤地层所夹的玄武质、硅质、生物碎屑碳酸盐岩中.对水银洞金矿赋矿地层岩石以及矿石显微组构进行了研究,矿石中主要载金矿物为细粒黄铁矿,具再生边、粒内孔隙、铸模孔隙结构及镶边生物矿化构造、铸模式生物矿化构造,是一典型的具沉积一成岩组构.金矿化与硅化有密切的成因联系,金与SiO2来源于峨嵋山玄武岩的喷溢活动,主要金矿体更多显示与峨嵋山玄武岩准同生特征.矿床为沉积一成岩弱改造成囚金矿床. 相似文献
206.
207.
中国对虾血细胞酶细胞化学的初步研究 总被引:1,自引:0,他引:1
运用电镜酶细胞化学技术 ,对中国对虾 (Penaeus chinensis)的血细胞和血清中的酚氧化酶、酸性磷酸酶、碱性磷酸酶和过氧化物酶的酶活性部位进行标记。实验结果显示 :酚氧化酶主要以酶原形式存在于大颗粒细胞的颗粒体中 ,酸性磷酸酶和碱性磷酸酶以酶原形式存在于小颗粒细胞的颗粒体中。健康虾和患病虾血细胞中酶活性的表现形式不尽相同 ,在病理情况下 ,颗粒细胞能以细胞解体的方式 ,排出细胞内的颗粒 ,转化成有活性的酶 ,以此提高血淋巴中这几种酶的活性。透明细胞可以吞噬排放颗粒后的颗粒细胞 ,透明细胞中由高尔基体合成的酸性磷酸酶等溶酶体酶主要用于透明细胞的细胞内消化作用。研究认为 :3种血细胞因含有不同的免疫酶以及酶的作用方式不同而具有不同的免疫功能 相似文献
208.
209.
210.
Study of zooplankton ecology in Zhejiang coastal upwelling system-Species distribution and diversity of zooplankton 总被引:2,自引:0,他引:2
The species distribution and diversity of zooplankton and the effects of hydrodynamic factors of Zhejiang coastal waters during the active period of upwelling are discussed.High dominance (low diversity), high biomass and short food chain were found in the landward margins of the central region of the upwelling. There were evident interactions between the distribution of zooplankton and the environmental factors. The expression of these interactions is that different ecotypes of zooplankton adapt to different hydrological situations. There is significant positive correlation between the diversity indices of zooplankton and the mean water temperature in the survey area. It is noted that the vertical distribution of Calanus sinicus indicates to a certain extent the colder water environment of the upwelling (Fig. 7, Table 2, Reference (Hargreaves, 1981). 相似文献