Underwater explosion effects of 60 mm H.E. mortar bomb on a cylindrical concrete structure-PIT

PIT tests are usually performed when a mass distribution of High Explosive(H.E) projectile fragments is required. This paper shows the underwater detonation effects of 60 mm, M90 H.E. mortar bomb filled with Comp. B on cylindrical concrete structure(concrete pipe closed at one end-similar to a PIT test)which is 2 m high(inner height) with inner diameter of also 2 m. Thickness of both wall and bottom of a pipe is 0.35 m. Detailed characteristics of concrete which is used for manufacturing of a pipe are specified. Mortar bomb is submerged directly in to the water(no free airspace around the bomb) with the nose pointing to the bottom of a pipe. Number and mass of fragments after detonation are presented by table and photographs. Fragments of dummy fuze, through which blasting cap was protruded, are collected and reassembled to form a shape of a fuze after detonation where expanding of fuze material due to a detonation products is visualized. After underwater detonation, detonation of the same mortar bomb is performed in an empty pipe and the effects of this kind of detonation are observed. Distance at which fragments generated from submerged mortar bomb will not reach concrete pipes wall is also determined.

Synthesis and Flocculation of Polyacrylamide with Low Water Absorption for Non-dispersible Underwater Concrete

The polyacrylamide which is directly added into concrete shows strong water absorption property.Thus the construction of underwater constructure would demand high amount of water,resulting in poor workability of concrete and strength shrinkage after hardening.Herein,a kind of anionic polyacrylamide(APAM)grafted with water reducing functional group(-COOH)was synthesized at low temperatures by partial factor design and response surface design.The structure and morphology of APAM were characterized by UV,FTIR and SEM methods.The experimental results show that the molecular weight of the synthesized APAM could reach 11 million,under the condition that the temperature was 35℃,the pH value was 8,the monomer concentration was 27wt%,the initiator dosage was 0.6wt%,and the monomer ratio(n(AM):n(AA))was 3.When the APAM was applied into the underwater slurry,it presented good flocculation and low water demand.When the dosage was 1%of the mass of the cement,the water demand increased by 12%,which could meet the self-leveling and anti-dispersity of the underwater slurry at the same time.This technology provides technical guidance for the large-scale industrial production of polyacrylamide for underwater concrete construction while achieving environmental protection during production.

Effect of GGBS on performance deterioration of non-dispersible underwater concrete in saline soil

In saline soil areas,there are a large number of ions in soil or water environments,such as Cl^(-)and SO_(4)^(2-),which have strong corrosive interactions with buildings.To study the deterioration of non-dispersible underwater concrete in sulfate,chloride,and mixed salt environments,the compressive strength and deterioration resistance coefficient of the studied concrete mixed with different amounts of ground granulated blast-furnace slag(GGBS)were analyzed in this paper.At the same time,the micro morphology and corrosion products distribution of the studied concrete were observed by means of SEM,plus XRD diffraction,TG-DTG and FT-IR analyses to explore the influence of corrosive solutions on the hydration products of concrete.We also analyzed the mechanism of improving the deterioration resistance of the studied concrete by adding GGBS in a saline soil environment.The results show that the compressive strength of the studied concrete in a chloride environment was close to that in a fresh water environment,which means that chloride has no adverse effect on compressive strength.The deterioration of the studied concrete was most serious in a sulfate environment,followed by mixed salt environment,and the lowest in a chloride environment.In addition,by adding GGBS,the compressive strength and deterioration resistance of the studied concrete could be effectively improved.

Analysis on Pore Structure of Non-Dispersible Underwater Concrete in Saline Soil Area

In this paper,mercury intrusion porosimetry(MIP)is used to test the pore structure of non-dispersible underwater concrete so as to study the influence of pouring and curing environment,age and slag powder on the pore characteristics of concrete,analyze the pore characteristics,porosity and pore distribution of concrete in different hydration stages,and reveal the relationship between pore structure and permeability of concrete.The results show that the pore-size distribution of concrete in fresh water condition is better than that in sulfate environment and mixed salt environment,and therefore,sulfate as well as mixed salt are not conducive to the development of pore structure of non-dispersible underwater concrete;chlorine salt has little effect on the pore structure of nondispersible underwater concrete;under the three conditions of sulfate,chlorine and mixed salt,the porosity of concrete mixed with slag powder is lower than that of concrete without slag powder.The results indicate that the addition of slag powder can ameliorate the pore size distribution of non-dispersed underwater concrete,reduce the porosity,and make the concrete structure more compact,which is beneficial to improve the permeability resistance of concrete at the macro level.

大直径水下盾构隧道水下不分散砂浆应用与效果分析

随着现代工程建设技术的发展,特殊砂浆作为一种性能优越的建筑材料,在工程中的应用越来越广泛。其中水下不分散砂浆在基岩裂隙水发育丰富、地下动水丰沛且受潮汐影响流动性强的地下工程建设中取得了较好的效果。依托广州海珠湾隧道工程大直径水下盾构隧道试验段,结合普通砂浆与水下不分散砂浆在相同环境使用下的情况,从室内试验、地质雷达扫描、地表沉降监测、管片错台、渗漏水、上浮等方面进行对比分析跟踪验证,来对水下不分散砂浆的可行性开展分析。

Preparation of High Performance Non-dispersible Concrete

A new-type underwater non-dispersible concrete admixture NDA was prepared,its function mechanism was analyzed,and C40 high performance non-dispersible underwater concrete was manufactured by applying NDA.The results indicate that NDA has a suitable workability,low strength loss,and excellent anti-dispersion;the fresh non-dispersible underwater concrete with NDA has high anti-dispersion,excellent workability such as self-compacting and not bleeding;hardened non-dispersible underwater concrete with NDA has a high strength,high durability such as high anti-abrasion,impermeability and anticorrosion.

低水温下大流动性环氧树脂水下修补砂浆的制备

水电站泄水建筑物水下修补施工对环氧树脂修补砂浆的流动性有更高要求,特别是低水温环境下仍然具有大流动性、可以自流平。选用Dinger-Funk方程优化填料粒径分布,优选粒径分布指数为0.4、紧密堆积空隙率仅0.251%的填料,将环氧树脂砂浆流动度提高到18.3 cm;增加稀释剂用量,由20份增加到40份,5℃下环氧树脂基液黏度显著降低73%,砂浆流动度由13.5 cm提高到17.0 cm;为了抵消稀释剂掺量增加和低温所导致的砂浆强度降低,添加30份三环氧官能团树脂增加树脂基液活性,5℃下砂浆的28 d水下粘结强度和抗压强度分别为2.9 MPa、88 MPa,相比未添加的分别提高142%、115%。

新型钢套箱围堰施工在月城河控制工程的应用

月城河控制工程上游分水墩及右侧翼墙水下浆砌块石部位,经过长时间的运行冲刷,已造成大面积损坏,出现严重的块石脱落现象,存在较大安全隐患。通过重点描述分水墩维修的施工过程,介绍一种无需打桩的钢套箱围堰,通过套箱侧板及底部封底混凝土为水中分水墩施工提供无水环境的新型施工方式。

重力式码头水下抛石体加固技术及检测研究

介绍了采用水下不分散水泥砂浆对码头水下抛石体进行高压注浆加固的方法。为了检测高压注浆加固效果 ,采用探地雷达、弹性波CT无损检测方法 ,配合所取岩芯的波速测试及点荷载强度试验 ,对码头水下高压注浆效果进行综合检测。研究结果表明 ,采用一定配合比及加有一定量的水下不分散剂的水泥砂浆加固水下抛石体 ,方法可靠、效果良好。弹性波CT、探地雷达用于水下高压注浆加固效果检测 ,检测结果直观、可靠 ,可用于其它用途的高压注浆效果检测。

适宜于高压饱水条件下的同步注浆材料性能研究

采用有机-无机复合技术原理,利用硅灰、羟乙基纤维素、聚丙烯酰胺3种物质进行复配,研制出一种新型抗水分散剂(KSF)。试验研究表明KSF可以使盾构隧道同步注浆单液砂浆具有良好的保水性和高抗水分散性能,新拌砂浆环境水溶液pH值最高为8.3,砂浆28d水陆强度比可达91%。

树脂涂层与混凝土基面粘结的研究

环氧砂浆涂层在水利水电工程中的应用已有 40年历史。根据工程需要 ,选用适当的材料和配方是保证成功的关键。为此 ,介绍潮湿、水下环氧砂浆和弹性环氧砂浆的工程应用情况 。

可水下固化环氧砂浆的制备与性能研究

选用活性稀释剂、低粘度固化剂及疏水改性填料制备了流动度大、疏水性好、力学性能及水下粘结强度优异的可水下固化环氧砂浆。研究了稀释剂、固化剂、填料、偶联剂用量及试验龄期对环氧砂浆力学强度及水下粘结性能的影响。结果表明:当m(E-51环氧树脂)∶m(692稀释剂)∶m(593固化剂)∶m(KH-560偶联剂)∶m(水泥)∶m(硅粉)∶m(细砂)=100∶15∶31∶7.5∶25∶100∶400时,制备的水下固化环氧砂浆性能最优,流动度为265 mm,适用期为75 min,抗拉强度为13 MPa,抗压强度为85 MPa,抗折强度为36 MPa,水下正拉粘结强度为3.0 MPa,界面破坏形式为混凝土内聚破坏,适用于桩基础水下环氧灌浆修复。

水下修补环氧混凝土配合比试验研究

文中以某水电站大坝溢流面及消力池大修工程为背景,根据工程实际分别设计了3组水下修补环氧混凝土和水下环氧砂浆的配合比,并研究了不同配合比水下环氧混凝土(砂浆)的抗压强度、抗折强度、与水泥混凝土粘结性能、耐环境作用能力以及其水下流动性能。研究表明:环氧树脂材料在混凝土混合物中的掺量对环氧混凝土的性能有重要的影响,综合考虑其力学性能指标及施工流动性等性能,提出工程实际混凝土推荐环氧树脂掺量为22.0%,砂浆环氧树脂推荐掺量为23.0%。

青岛港八号码头空心方块断裂缝水下修补试验研究

本文提出的水下修补方案及水下修补材料,经室内试验和现场应用表明,该水下修补材料具有良好的抗分散性、较高的力学强度和耐久性;水下修补施工简便,可操作性强;用水下不分散砂浆,可以有效地固结空心方块内的抛填块石,大大提高块体的承载力。

水下明挖隧道防水层的选择

结合南京、杭州的三条已建成通车的水下隧道防水层的设计,分析了隧道防水层选择时所要考虑的一些问题。

水中爆炸对围岩增耦的实验研究

为研究水中爆炸对围岩的增耦,在一个直径1.6 m的水泥砂浆半球体装置上,将其中心预留的直径0.3 m的腔室内注水和置入水泥砂浆芯体,对比性地进行了一系列的1.00 g TNT(2,4,6—三硝基甲苯)当量的填实和空腔爆炸实验。水泥砂浆球表运动测量数据表明,与水泥砂浆中的空腔解耦相比,水中空腔爆炸的解耦效果较差,尤其水腔中爆炸可大大增强爆炸能量的耦合。可以推断,水下爆炸会明显增强围岩中的爆炸应力波强度,近水域中的空中爆炸也可能会增强围岩中的爆炸能耦合,因而相对于围岩和堤坝中同距离、同药量的爆炸来讲,所引起的破坏危险更大。

大口径排水管涵修复技术与修复材料

综述了原位固化(Cured In Place Pipe,CIPP)法、穿插法、内衬法、无机防腐砂浆喷涂法、套环法、注浆法和Pipere-100内涨圈柔性内修复法共7种国内常用大口径管涵非开挖修复技术,以及Rib Loc螺旋缠绕技术和Pattem Flooring技术等国外常用大口径管涵非开挖修复技术,并结合文献和作者的研究成果,提出用于水上部分修复的快速修复砂浆和用于水下部分修复的水下抗分散修复砂浆。

一种适合混凝土水下修复的新型环氧砂浆

水工混凝土建筑物由于运行环境的复杂性,普遍存在水下开裂破损等病险。为不影响建筑物运行,尽可能选择在水下修复,其关键是选择适宜的修复材料。为此研发了一种适合水下混凝土修复的新型环氧砂浆,并通过试验研究了其主要力学性能及主要影响因素。试验结果表明:新型环氧砂浆3 d无侧限抗压强度达到60 MPa以上;当胶固比为1∶2.5时,水下浇筑的环氧砂浆黏接强度最大,超过了3.0 MPa;当胶固比为1∶3.5时,环氧砂浆的抗冲磨强度(水下钢球法)最大,达到847.800 h/(kg/m2)。性能测试及实际工程应用表明:新型环氧砂浆具有抗压强度高、水下黏接(与混凝土)强度大、抗冲磨效果好等特点,能够与旧混凝土协调工作。在具体工程中,可根据不同的病险类型,选择适宜的胶固比及有关施工参数。

环氧树脂乳液改性水泥基水下修补砂浆的制备与性能研究

采用环氧树脂乳液对硫铝酸盐水泥基水下修补砂浆进行改性,研究了聚灰比对修补砂浆凝结时间、水下分散性和抗折粘结性能的影响,并通过扫描电镜(SEM)观察了环氧树脂乳液改性砂浆的微观结构。结果表明:随着聚灰比的增大,砂浆凝结时间延长;聚灰比为0.1以内时,硫铝酸盐水泥基修补砂浆的水下抗分散性增强、抗折粘结强度大幅度提高,而继续增大聚灰比,抗折粘结强度反而降低。SEM观察表明,环氧树脂可在水泥水化产物和砂粒表面形成连续的聚合物膜,但环氧树脂乳液掺量过大(聚灰比为0.2)时,形成的聚合物膜过厚,反而降低了砂浆与旧基层的粘结性。

水性环氧砂浆抗冲磨特性研究

水性环氧砂浆在水工建筑领域得到了越来越多的关注和应用,其物理力学特性尤其是抗冲磨特性是决定是否应用于排沙隧洞、溢流坝面等泄水建筑物的关键因素。针对水性环氧砂浆的抗冲磨性能,采用高速水下钢球冲磨仪模拟推移质对水性环氧砂浆的抗冲磨破坏,分析在不同转速、不同级配冲磨钢球下砂浆的抗冲磨特性,探索了适合于水性环氧砂浆的水下钢球法试验参数,提出了水性环氧砂浆抗冲磨寿命预测方法。