石材修补

大理石和花岗石色泽鲜艳、花纹细腻清晰、组织细密坚实、光泽晶莹;具有耐磨、抗震、耐风雨浸蚀、耐腐蚀、抗压和非磁性等特性,是一种优良的天然材料。

Load-bearing characteristics and energy evolution of fractured rock masses after granite and sandstone grouting

Experiments on grouting-reinforced rock mass specimens with different particle sizes and features were carried out in this study to examine the effects of grouting reinforcement on the load-bearing characteristics of fractured rock mass.The strength and deformation features of grouting-reinforced rock mass were analyzed under different loading manners;the energy evolution mechanism of grouting-reinforced rock mass specimens with different particle sizes and features was investigated;the energy dissipation ratio and post-peak stress decreasing rate were employed to evaluate the bearing stability of grouting-reinforced rock mass.The results show that the strength and ductility of granite-reinforced rock mass(GRM)under biaxial loading are higher than that of sandstone-reinforced rock mass(SRM)under uniaxial loading.Besides,the energy evolution characteristics of grouting-reinforced rock mass under uniaxial and biaxial loading mainly could be divided into early,middle,and late stages.In the early stage,total,elastic,and dissipation energies were quite small with flatter curves;in the middle stage,elastic energy increased rapidly,whereas dissipation energy increased slowly;in the late stage,dissipation energy increased sharply.The energy dissipation ratio was used to represent the pre-peak plastic deformation.Under uniaxial loading,this ratio increased as the particle size increased and the pre-peak plastic deformation of grouting-reinforced rock mass became larger;under biaxial loading,it dropped as the particle size increased,and the pre-peak plastic deformation of grouting-reinforced rock mass became smaller.The post-peak stress decline rate A_(v) was used to assess the post-peak bearing performance of grouting-reinforced rock mass.Under uniaxial loading,parameter A_(v) exhibited reduction as the particle size kept increasing,and the ability of post-peak of grouting-reinforced rock mass to allow deformation development was greater,and the bearing capacity was greater;under biaxial loading,A_(v) increased with the particle size,and the ability of post-peak of grouting-reinforced rock mass to allow deformation development was low and the bearing capacity was reduced.The findings are considered instrumental in improving the stability of the roadway-surrounding rock by granite and sandstone grouting.

张大千先生在青海

前不久,在我国台湾省病故的当代国画大师张大千先生,曾于一九四一年春同他的夫人、长子心智、女婿肖建初等人,翻越关山、陇云抵达东方的艺术宝库敦煌。准备把沉睡在那里千余年的魏、唐壁画临摹下来。 但是由于他所携带的绘画材料远远不够使用,只好回兰州卖画筹资买画料。当时有人告诉他,只有青海塔尔寺,才能解决这个困难。 一九四一年夏,大千先生来到青海塔尔寺,立刻被大小金瓦寺的辉煌古建筑和精美的壁画、雕塑艺术所吸引。在这里,他不仅采购了大量石青、石绿、

“有……是……”格式的误用

“有……”、“是……”两个述宾结构连起来可以构成递系结构(兼语式): 有人是今天走的。(1)这种句式的句子一长,就容易犯结构混乱或一些语法书上称之为“杂糅”的毛病。例如: 中国科学院及湖北省博物馆等有关单位的科学工作者立即前往发掘和清理,搜集到大量石制工具,其中有砍石器、石核、石片等是用石英岩卵石、石英砂岩、燧石等原料打制成的。(2)这种错误改正并不难。可以在头一个“等”后隔断,在“是”前补出“这些都”或“它们都”。 问题是(1)和(2)同时按“有……是……”格式组成,何以一对一错?考察这种格式组成的递系结构,正确的句子不外乎下列两种情况:

我国文字起源又推前2000年

我国文字起源又推前２０００年湖北考古工作者最近在宜昌县杨家湾遗址发现我国最早象形文字，把文字起源推到６０００年前，比商代殷墟甲骨文还早２０００多年。考古队员从该遗址中发掘出大量石器、玉器，还发现１７０余种刻划在陶器上的符号。这些符号记录当时人们对生活...

世界

日前,伊拉克驻俄罗斯大使宣布,俄罗斯将与伊拉克签署总额为600亿美元的互助经济协议,在10年中,俄罗斯与伊拉克将在石油、天然气、运输、通信等部门进行67项合作。

Overcharge performance of LiMn_2O_4/graphite battery with large capacity

The LiMn2O4/grapbite battery was fabricated and its 3 C/10 V overcharge performance was studied. Spinel LiMn2O4 was synthesized by solid-state method and 325680-type size full battery was fabricated. The structure and morphology of the powders were characterized by XRD and SEM technique, respectively. The battery explodes after 3 C/10 V overcharged test, and surface temperature of the battery case arrives at 290 ℃ in 12 s after exploding. Black air is given out with blast. Carbon, MnO, and Li2CO3 are observed in the exploded powders. The cathode electrode remains spinel structure with 5.0 V charged. Cracks in the cathode electrode particles are detected with the increase of voltage by SEM technique. The 5.0 V charged electrode can decompose into Mn3O4 at 400 ℃. It is demonstrated that the decomposition of 5.0 V charged electrode can be promoted and Mn^4＋ can be deoxidized to Mn^2＋ by carbon and electrolyte through the simulation of blast process.

Underground mining of thick coal seams

This paper reviews underground mining methods for total thickness of a thick coal seam in single lift （TI＇rCSSL）. Review shows the required engineering for extraction of thick seams needs to be fitted with thickness of the seam, behavior of rock-mass and surrounding stress conditions for efficient mining. Variants of TI＇rCSSL are able to extract a maximum 10-12 m thickness only. An improvement in bending moment of the overlying coal band in longwall top coal caving （LTCC） provides better under-winning opportunity for the roof coal band. An acceptable limit of 25 MPa compressive strength of coal for the success of LTCC may be increased under favorable geo-technical conditions. Bord and pillar in India adopted induced caving of roof coal band for single lift depillaring of total thickness （SLDTr） of a compe- tent thick coal seam developed along floor. Case studies are given to arrest the adverse effects of extrac- tion height on pillars.

Experimental study on removal nitrogen oxide of flue gas by using solid absorbents

With the rapid development of modem industry and increase of consumption of the coal, petroleum and natural gas etc., emission of nitrogen oxide （NOx） from flue gas has air environment quality worsen day by day. This research work is experimental study on removal low concentration NOx of flue gas by using solid absorbents. The experiment result shown that denification rate by modified activated carbon is higher than that of modified zeolite and rectorite. Average denitrification rate is 65.47% and maximum denitrification rate is 95.82% for activated carbon; average denitrification rate is respectively as 43.29% and 36.18%, maximum denitrification rate is respectively as 87.51% and 79.47% for modified zeolite and rectorite. Experiment results indicated that NO adsorption process of activated carbon can be described by Freudlich adsorption mode, K=0.143 and n=2.842 and Freudlich adsorption isotherm equation is： q = 0.143MO^0.3519.

油罐火车防火安全措施

1994年3月8日,瑞士一列由20节装满石油的油罐组成的货车正向苏黎士市火车站驶去。距车站不远处时,司机发现刹车气动压力下降,制动杯摇动,当即紧急刹车,这时油罐车厢冒起了大片黑色浓烟。当司机走出列车时,眼前发生的特大事故使他惊恐万状。