路基路面宽裂缝处治新结构和新材料

通过研究并优选结构和新材料技术来处治路基路面宽裂缝,并实施试验路跟踪验证。对于纵向路基宽裂缝,沿纵缝中央和两侧钻孔、灌注聚合物改性水泥浆液,然后铺筑土工布和加铺沥青层,试验路使用5 a,效果良好无反射裂缝;对于横向裂缝,在裂缝两侧钻孔灌注超细水泥注浆材料、同时沿横缝开槽后灌注高渗透改性环氧树脂注浆材料,切槽后铺筑抗裂贴、加铺沥青层,试验路使用完好无反射裂缝。高渗透改性环氧树脂注浆液渗透性强,无压力作用下可渗入固结级配碎石基层15 cm左右,适用于处治路面结构内部隐形松散缺陷。

在结构设计裂缝控制中高强钢筋应用的影响

高强度钢筋指的是:HRB400级和RRB400级钢筋,根据混凝土结构设计规范GB50010-2002规定的裂缝计算方法和相应的构造方法措施,对地下和地上结构在受弯条件下的钢筋用量进行控制.在此主要浅介HRB400级钢筋的使用要求.

高强钢筋在结构设计裂缝控制应用中的影响

高强度钢筋指的是:HRB400级和RRB400级钢筋,根据《混凝土结构设计规范》(GB50010-2002)规定的裂缝计算方法和相应的构造方法措施,对地下和地上结构在受弯条件下的钢筋用量进行控制。在此主要浅介HRB400级钢筋的使用要求。

疏松砂岩稠油油藏的无筛管压裂技术

针对疏松砂岩稠油油藏低产、出砂的开发难题,研究开发了压裂防砂一体化技术,通过一趟管柱对疏松砂岩地层进行脱砂压裂,再挤入树脂涂覆砂对缝口以及射孔孔眼进行固结,以达到改善地层流动性能与防砂的双重效果。该技术在八面河油田的现场应用结果表明该技术成熟可靠,简化了施工工序,缩短了施工周期,具有显著的增产防砂效果。

沈阳油田高渗油藏端部脱砂试验应用

沈阳油田多个高渗砂岩区块井入高含水期,相比国内同类油藏采收率、采油速度均较低,制约油藏高效开采的重要因素是生产井段长(平均达到350~650米),层间矛盾大,致使高渗透、高流压、高产液、高含水油层占了主导作用,低渗透、低含水油层未能得到有效动用;油层非均质性强,导致平面、纵向动用程度差。针对以上问题,开展了端部脱砂工艺试验,达到造“短宽裂缝”的目的,提高了油井在平面上和纵向上的动用程度,进而提高油井单井产量,取得了较好的应用效果,为中高渗砂岩区块提高采收率开辟了一条新的途径。

数字图像处理在核电厂安全壳外观检查中的应用

确定了核电厂安全壳不可达区域远程遥测技术方案;为减少裂缝测宽的误差,研究了基于Image J平台的数字化处理对裂缝宽度进行定量分析的方法,论证并确定多因素影响下裂缝宽度的多参数行为,并用标准裂缝对比尺验证此方法的可行性,最终应用于核电现场工程项目。数据结果表明:该数字图像处理方法可大幅度减小当前国内远程遥测技术裂缝测宽的误差。

Crack detection of reinforced concrete bridge using video image

With the digital image technology,a crack detection method of reinforced concrete bridge was studied for the performance assessment.The effects including the image gray level,pixel rate,noise filter,and edge detection were analyzed considering cracks qualities.A computer program was developed by visual C++6.0 programming language to detect the cracks,which was tested by 15cases of bridge video images.The results indicate that the relative error is within 6%for cracks larger than 0.3 mm cracks and it is less than 10%for crack width between 0.2 mm and 0.3 mm.In addition,for the crack below 0.1 mm,the relative error is more than30%because the bridge is in safe stage and it is very difficult to detect the actual width of crack.

Properties and calculation of normal section bearing capacity of RC flexural beam with skin textile reinforcement

In order to overcome the wide crack of ordinary reinforced concrete (RC) at service stage which affects the service performance and durability of structures,a kind of concrete structure with skin textile reinforcement is proposed,namely a part of concrete cover of RC members is replaced by textile reinforced concrete (TRC).The flexural experimental results indicate that when the reinforcement ratios of steel bars are constant,compared with control beams,the average value of crack loads of the beams,whose reinforcement ratios of textile are 0.018%,0.036% and 0.055%,increases by 15.5%,20.4% and 31.1%,respectively,the average value of yield loads respectively increases by 12.5%,19.9% and 21.1% and the average value of ultimate loads respectively increases by 8.5%,26.0% and 44.0%,respectively.Considerable reduction in cracks width and spacing is observed for specimens with a TRC layer,and when the beams yield,the maximum crack width of the beam with textile stuck no sand and the beam with textile stuck sand is reduced by around 60% and 70%,respectively.Surface treatment of textile and mixing polypropylene fiber into fine grained concrete contribute to enhance the service performance of the flexural element.Embedding U-shaped hoop has almost no effect on the control of the crack width.Finally,the calculation method of ultimate bearing capacity of this flexural component with TRC layer was presented.Comparison between the calculated and the experimental values reveals satisfactory agreement,and the maximum error is no more than 6%.

Evaluation of parameters affecting reflection cracking in geogrid-reinforced overlay

The influence of the most important parameters on the service life of reinforced asphalt overlay with geogrid materials in bending mode was examined by employing the Taguchi method and analysis of variance techniques. The objectives of this experiment was to investigate the effects of grid stiffness, tensile strength, coating type, amount of tack coat, overlay thickness, crack width and stiffnesses of asphalt overlay and existing asphalt concrete on propagation of the reflection cracking. Results indicate that the stiffnesses of cracked layer and overlay are the main significant factors that can directly improve the service life of an overlay against the reflection cracking. Generally, glass grid is more effective in reinforced overlay than polyester grid. Effect of crack width of the existing layer is significant when its magnitude increases from 6 to 9 mm.

Chloride diffusivity in flexural cracked Portland cement concrete and fly ash concrete beams

In order to examine the effect of load-induced transverse cracks on the chloride penetration in flexural concrete beams, two different concretes, Portland cement concrete(PCC) and fly ash concrete(FAC), were tested with various crack widths. Total 14 reinforced concrete(RC) beams, ten of which were self-anchored in a three-point bending mode, were immersed into a 5% NaCl solution with the condition of dry-wet cycles. Then, the free chloride ion contents were determined by rapid chloride testing(RCT) method. Based on the proposed analytical models of chloride penetration in sound and cracked concrete subjected to dry-wet cycles, the apparent chloride diffusion coefficient and chloride diffusivity of concrete were discussed. It can be found that the performance of chloride diffusivity in both concretes will be improved with the increase of crack width, and that the influence of convection action will also be augmented. Based on the two samples obtained in sound concrete after 15 and 30 cycles, the time-exponent, m, for chloride diffusion coefficient was determined to be 0.58, 0.42, 0.62 and 0.77 for PCC1, PCC2, FAC1 and FAC2 specimens, respectively. Finally, two influencing factors of fly ash content and crack width on chloride diffusivity were obtained by regression analysis of test data, and it can be seen that factors kf and kw can be expressed with quadratic polynomial functions of fly ash content, f, and crack width, w, respectively.

Properties of Rattan Cane Reinforced Concrete Facade Subjected to Axial Loading

The use of steel reinforced concrete facade is gradually becoming unpopular because of the damage caused to the elements as a result of corrosion of the steel reinforcement. It is now possible to build lightweight and slender concrete structures which are invulnerable to corrosion with the use of fiber reinforcements, which are gradually replacing the corrosion prone steel. This paper describes the construction of faqade panels made of rattan cane reinforcements and steel reinforcements, ten number model sized elements of area 0.15 m2 and a depth of 40 mm were considered, with five panels for each reinforcement type. The elements were subjected to incremental load of 1 kN until failure occurred. Deflections were measured for each element, and crack width was measured at failure load. The results for both types of reinforcements when compared showed the rattan cane reinforced panels failing earlier than the steel reinforced panels. However a lower defection and crack width was recorded in the rattan cane reinforced panel. This paper concludes that the lower crack width formed after failure in the rattan cane reinforced panel gave it advantage over the steel reinforced panel, since it has lower space for the ingress of water which is the main agents of corrosion.

沥青层厚与基层对低温缩裂的影响

本文通过对沈本试验路径面冬季预测结果，分析了沥青层厚和基层对低温缩裂的影响；提出了沥青层厚和基层是影响沥青路面开裂宽度的重要因素．

Comparison of Crack Width and Space between SCC and Conventional Concrete Beams

Concrete is a material which is in wide use in engineering especially in construction engineering and road infrastructure facilities. Development trends for high rise constructions, modern skyscrapers indicate that building such constructions with normal concretes and low consistency is impossible, therefore there is a need for concrete with high processes because of great amount of reinforcement in cross-section of concrete elements. Solution for such construction is self-compacting concrete because of its ability to fill good formworks without compaction and vibration. Considering this fact, researches for cracks, mechanical characteristics of concrete and deformations have been conducted worldwide. In this paper, we conducted an experimental research to determine the cracks on beams of self-compacting concrete and compared it with conventional concrete. The experimentally-obtained results will be presented for both types of concrete for： module of elasticity, compression strength, crack with and cracks spacing for duration failure testing time t = 400 days.

A Comparative Study on the Flexural Behaviour of Waffle and Solid Slab Models When Subjected to Point Load

The determinations of flexural behavior of some engineering structures are based on different theories and equations, but it has been observed that some of these equations may not give true representation. This work has looked into the difference that may occur between theoretical and experimental results. An experimental test carried out on models of waffle and solid slabs structures were described and results from twenty test samples are presented. Each specimen was subjected to an incremental axial loading of 1 kN interval after 28 days of casting. The flexural moments, deflections and crack width at failure were obtained. The experimental flexural crack and theoretical flexural cracks for both types of slabs were compared. The result for flexural moments for waffle was 5.526 kNm, while solid slab was 3.684 kNm. The deflections showed that waffle slabs has 3.64 mm while solid has 9.28 mm, hence waffle has a higher structural stiffness than solid slabs, but the flexural cracks did not give the same results especially for the estimated crack width. It was concluded that estimated results based on developed equations may not be accurate because it is based on ideal situation.

Calculation of corrosion rate for reinforced concrete beams based on corrosive crack width

This paper deals with a correction method for corrosive crack width caused by non-uniform corrosion. Considering the corrosion cracking characteristics of a reinforced concrete structure, a correction model of corrosive crack width involving the mutual impacts between adjacent measuring points is established. The calculation model for steel bar corrosion rate for single point is obtained through quantitative analysis and accelerated corrosion tests on more than 70 reinforced cubic members. Two methods are suggested by combining two models, the correction and the corrosion calculation ones. Electrolyte accelerated cor- rosion tests on seven beams are carried out to verify these methods. The experimental results show that the ratio between the maximum corrosion rate by the indirect method and the measured average value ranges from 1.4 to 2.4, and the indirect method is shown to be an effective method for calculating the maximum corrosion rate.

Numerical study on flexural behaviors of steel reinforced engineered cementitious composite(ECC) and ECC/concrete composite beams

Engineered cementitious composite(ECC)is a class of high performance cementitious composites with pseudo strain-hardening behavior and excellent crack control capacity.Substitution of concrete with ECC can largely reduce the cracking and durability problems associated with brittleness of concrete.In this paper,a simplified constitutive model of the ECC material was applied to simulate the flexural behaviors of the steel reinforced ECC and ECC/concrete composite beams with finite element method.The simulation results are found to be in good agreement with test results,indicating that the finite element model is reasonably accurate in simulating the flexural behaviors of the steel reinforced ECC flexural members.The effects of the ECC modulus,ECC tensile ductility,ECC thickness and ECC position on flexural behaviors in terms of ultimate moment,deflection and the maximum crack width of the steel reinforced ECC or ECC/concrete composite beam are hence evaluated.

短纤维增强的高延性混凝土:发展、检测及应用

短纤维增强的高延性混凝土是一种新型高性能水泥基材料。在拉应力作用下,此种混凝土呈现高延性,其断裂伸长与普通纤维混凝土相比,可高达后者的100多倍。高延性混凝土除了具有高变形能力及高抗拉、抗剪强度外,直到断裂其裂缝的宽度仍然很低。此种新型混凝土可使特殊应用领域建筑物的设计、构造与测定以及修复发生彻底的变革。本文概述此种新型纤维混凝土的材料学原理、性能及应用前景。

水力压裂微注测试“水击效应”分析法及应用

通过阿根廷San Jorge盆地水力压裂微注测试资料分析发现:分析停泵瞬间泵压曲线的“水击效应”,能够快速定性分析液体造缝缝宽、造缝空间情况及加砂的难易程度。与常规压力恢复测试及小型压裂测试方法相比,成本低、效率高、测试方法简单快捷。