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91.
Tree stem (>2 m tall) mortality was assessed following a late dry‐season wildfire across a seasonally flooded elevation gradient at Workshop Jungle, near Darwin, in the Northern Territory of Australia. For all species combined, dead stems had significantly smaller diameter at breast height (dbh) than living stems. Assessment of tree‐stem damage following a tropical cyclone at Cobourg Peninsula, NT, revealed that damaged stems had significantly greater dbh than undamaged stems for all tree species sampled across a boundary between monsoon rainforest and savanna. A greater proportion of stems were damaged by the cyclone than by the fire (28 per cent as against 18 per cent), although there were considerable between‐community differences in the proportion of damaged stems at the two sites. The fire caused little impact (<10 per cent) on total basal area of three different forest communities on the elevation gradient at Workshop Jungle. The cyclone was found to cause >50 per cent damage to total basal area of three different communities on Cobourg Peninsula. It is suggested that the combination of a cyclone followed by an intense fire in storm debris could potentially destroy a monsoon rainforest through its impact on all tree‐size classes. This may explain why some monsoon rainforests rapidly contracted following Cyclone Tracy that destroyed the city of Darwin on Christmas Day, 1974. 相似文献
92.
论述了岩体损伤力学在岩体力学中的地位,并从细观和宏观两个方面系统介绍了其最新研究进展;对岩体损伤力学研究中的几个重要问题提出了见解,认为分形几何是研究损伤的有效手段。 相似文献
93.
94.
基于珠江三角洲通信建筑物的调查资料,对典型的通信建筑物做了时程地震反应分析和单体震害预测;对另一些建筑物做了群体震害预测;并就通信设备震害预测问题做了简单评述。 相似文献
95.
1993年8月7日沐川凤村5.0级地震前,省、市地震部门曾提出过中短期预测意见。事实表明所作判断在一定程度上是准确的。震后进行了现场考查及震害评估。其震中烈度为Ⅶ度,震中区呈近东西向椭圆形。地震造成3人受伤,总经济损失达1082.2万元。 相似文献
96.
Yoshinobu Tsuji Fumihiko Imamura Hideo Matsutomi Costas E. Synolakis Puspito T. Nanang Jumadi Satoshi Harada Se Sub Han Ken'ichi Arai Benjamin Cook 《Pure and Applied Geophysics》1995,144(3-4):839-854
A field survey of the June 3, 1994 East Java earthquake tsunami was conducted within three weeks, and the distributions of the seismic intensities, tsunami heights, and human and house damages were surveyed. The seismic intensities on the south coasts of Java and Bali Islands were small for an earthquake with magnitudeM 7.6. The earthquake caused no land damage. About 40 minutes after the main shock, a huge tsunami attacked the coasts, several villages in East Java Province were damaged severely, and 223 persons perished. At Pancer Village about 70 percent of the houses were swept away and 121 persons were killed by the tsunami. The relationship between tsunami heights and distances from the source shows that the Hatori's tsunami magnitude wasm=3, which seems to be larger for the earthquake magnitude. But we should not consider this an extraordinary event because it was pointed out byHatori (1994) that the magnitudes of tsunamis in the Indonesia-Philippine region generally exceed 1–2 grade larger than those of other regions. 相似文献
97.
耗能-隔震柔性底层钢管混凝土-钢筋混凝土组合框架的实验研究 总被引:1,自引:1,他引:1
本文用钢管混凝土柱作为结构底层耗能柱、用承重墙和隔震器控制结构底层倒塌破坏,从而提出了一种新的耗能-隔震柔性底层结构体系。通过本文12根钢管混凝土柱和文献[7]中7根钢管混凝土柱的低周疲劳实验,初步确定了钢管混凝土柱地震损伤模型的参数;通过两个钢管混凝土-钢筋混凝土三层框架模型和一个纯钢筋混凝土三层框架模型的拟动力实验,研究和比较了两类结构体系的地震损伤。 相似文献
98.
A Combined Three-Dimensional Geological-Geostatistical-Numerical Model of Underground Excavations in Rock 总被引:1,自引:1,他引:1
Summary. This paper exploits geological and borehole geotechnical data obtained in the exploratory phase of a tunneling project to
investigate in a first place if the kriging interpolation scheme may effectively reproduce the spatial variability of rock
mass quality (Rock Mass Rating, RMR) in the vicinity of tunnels. For this purpose a quick solver in Fortran has been developed
that performs variography analysis of 3D spatial data, fast kriging estimations of RMR between borehole sampling locations
at the centroids of the elements of the numerical model, and model validation. For the purpose of an integrated underground
excavation design, a step further is made by incorporating into the 3D mechanical numerical model of the rock mass, the three-dimensional
(3D) solid geological model, thus coupling the geology with the ground (geotechnical) model (i.e. each element of the numerical
model is assigned a geological material). The mechanical properties of each finite difference cell (or Representative Elementary
Volume) of the ground model were then prescribed according to its geological type, the spatial heterogeneity of the rock mass
expressed quantitatively with the kriging model, and the upscaling calculations of the mechanical properties of the intact
rocks determined in the laboratory, based on the size-effect (strength dependence on size) and Damage Theory. Furthermore,
a preliminary numerical simulation of the advance of unsupported tunnels in the model of the heterogeneous rock mass was performed
for illustration purposes. 相似文献
99.
Summary. Conventional blasting causes cracks and fractures in the rock. Controlled blasting techniques produce the macrocrack in a
desired direction and eliminate microcrack in the remaining rock. Macrocrack development in desired direction is required
for extraction of dimensional stone and at the same time there is need to reduce microcrack development in the block and remaining
rock. To achieve the objectives, experimental work in the quarries was carried out for separating marble block from the in
situ strata as practiced in some of the Indian mines by using detonating cord of 30 to 50 g/m by varying hole spacing, hole
diameter, air cushioning, water and sand filled blast-holes. Blasthole notching was carried out. Further, tests were carried
out by using various liners inside the blasthole to determine the damages in the extracted block and remaining rock. The designed
experimental work was undertaken and rock samples were collected by coring before and after blasting for quantification of
microcrack in the rock. P-wave velocity and microscopic studies were conducted for quantification of damages. Experiments
were also conducted at laboratory scale for the quantification of damages in single circular and notched holes with variation
of stemming and liners. The P-wave velocity close to hole always reduces after blast and in case of NG-based charge and detonating
cord it decreases up to 1/3rd. With PVC pipe and paper tube liners decrease is negligible. Thus, by using notched hole with paper tube, decrease in P-wave
is minimum indicating least damage. 相似文献
100.
Päivi Mäntyniemi 《Journal of Seismology》2007,11(2):177-185
This study investigates the effects of the Fennoscandian earthquake that occurred on 4 November 1898 (GMT) on Tornio in Northern
Finland. The extra fire inspection conducted in the town on 21, 22 and 23 November 1898 provided insight into the failures
caused by this low-magnitude earthquake. The building stock was of timber with masonry stone components. More than 30 heating
units sustained damage. The macroseismic intensity in Tornio is estimated at I = 6 (European Macroseismic Scale). 相似文献