Research on Technique of Pre-judge for Waterlogging of Highway Along River in Mountainous Areas Zhi-dong GUO 1, Di WANG 2,* and Yang ZHAO 2

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1 nd International Conference on Test, Measurement and Computational Method (TMCM 2017) ISBN: Research on Technique of Pre-judge for Waterlogging of Highway Along River in Mountainous Areas Zhi-dong GUO 1, Di WANG 2,* and Yang ZHAO 2 1 Transportation Bureau of Ji Zhou District, Tianjin , China 2 College of Civil & Transportation Engineering, Hebei University of Technology, Tianjin , China *Corresponding author Keywords: Highway in mountains areas, Along river, Water damage, Pre-judging. Abstract. This paper gives statement about methods that how to recognize if the highway along river is destroyed by water damage, which on the basis of analyzing factors of water damage and pre-judge model of highway along river, then analyzes the result combine with application of JiBei mountain area, verifies its scientificity and effectiveness. Subgrade of highway along river in mountains areas suffers from long-term or discontinuous effect of soaking caused by running water. Under soaking effect of discontinuous water flow, running water porous flows into subgrade through slope of subgrade, then unit weight of backfill materials(γ), cohesive force(c) and internal friction angle(φ) change suddenly, those factors bring down the mechanic strength indexes of subgrade soil, in this case, subgrade softens like rubber road or occurs the lateral movement, then surface of highway cracks, subgrade starts sinking, spring of subgrade frosts boiling. There are two effects exist in washout result. One is water flows past surface of subgrade slope; the other is washing effect to toe of slope, which is caused by swirling flow and vortex resulting from river bend. Establishing scientific, effective pre-judging and identification system becomes more and more significant and important to build scientific pre-judging model which aims at different geographic areas and guides the deployment of prevention work. Introduction There are a lot of rivers, valleys and highways along river within the scope of our homeland, different levels of water damage along river slope will appear under the of flood rush caused by rainstorm. Subgrade of highway along river in mountains areas suffers from long-term or discontinuous effect of soaking caused by running water. Under soaking effect of discontinuous water flow, running water porous flows into subgrade through uncompacted slope of subgrade, then unit weight of backfill materials(γ), cohesive force(c) and internal friction angle(φ) change suddenly. It is unable to estimate water damage loss which is caused by natural forces arise from rainstorm and flood act on highway along river, so establish scientific, effective pre-judging and identification system will prevent disasters and reduce damages and loss. Therefore, it becomes more and more significant and important to build scientific pre-judging model which aims at different geographic areas and guides the deployment of prevention work. Influence Factors about Water Damage of Highway Along River 1Rainfall factor(j) According to the analyzation about rainfall data of Tianjin mountain areas, choose five rainfall factors. According to characteristics of distribution in total about number of rainy days and its impact on highway along river and span the gully, combining with experts opinions and putting into 5 degrees, the effect is assigned in the table 1 below. 78

2 Table 1. Rainfall factor level partition table. Level of rainfall factor(j) <1d 1~3d 3~7d 7~15d >15d Influence degree Weak weak Medium strong Strong degree Plants coverage factor(z) The larger plants coverage is, the lower possibility and harmfulness of water damage of highway in mountains areas are. According to total characteristics of distribution about forest vegetations and its impacts on highways which along river and span the gully in JiZhou, combining with expert opinions and putting into 5 degrees, assignment is in the table 2 below. Table 2. Plants coverage factor level partition table. Level of Plants coverage factor(z) >80% 50%~80% 20% ~50% 5%~20% 0%~5% Influence degree Weak weak Medium strong Strong degree Drainage density factor(h) Drainage density can overall reflect run-off strength of one area, the bigger drainage density of area is, the greater run-off strength of river is, building highway along river or bridge and culvert takes a greater proportion, the possibility of highway damaged by water will be higher. Drainage density is the total drainage length per unit area(1km 2 ). According to characteristics of distribution and experts opinions, its on highway in mountains areas is divided into 5 levels, assignment is in the table 3 below. Table 3. Drainage density factor level partition table. Drainage density factor(h,m/ km 2 ) >3500 Influence degree Weak weak Medium strong Strong degree Valley proportion factor (G) In JiZhou, the area of mountains areas accounts for more than 51 percent of total area, the proportion of valleys which topographic slope is greater than 25 degrees is large. Areas that own large valley proportion, those water run-off strength are also large. According to characteristics of distribution,its on highway in mountainous areas is divided into 5 levels, assignment in the table 3 below. Table 4. Valley proportion factor level partition table. Valley proportion factor(g) <0.1% 0.1%-3% 3%-20% 20%-40% >40% Influence degree Weak Medium Strong weak strong degree Model Ensures the Areas where Appear Waterlogging of Highway in Mountainous Areas Basing on the analyzation of four factors, which are rainfall factor, plants coverage factor, drainage density factor and valley proportion factor, take those factors into consideration which have effect on water damage of highway in mountains areas, then comprise river run-off strength index through a weighted summation of four factors, specific formula is 4-3 below: Hc=J w1+z w2+h w3+g w4 (1) In the formula: H c expresses river run-off strength index, J expresses value of rainfall factor, Z expresses value of plants coverage factor, H expresses value of drainage 79

3 density factor, G expresses value of valley proportion factor ; w 1, w 2, w 3, w 4 specify the weight coefficient of rainfall factor, plants coverage factor, drainage density factor and valley proportion factor. According to experts opinion survey, getting the weight of river run-off strength index factors at table 5. Influence factor Rainfall(J) Table 5. Weight of each factor. Plants coverage(z) Drainage density(h) Valley proportion(g) weight According to characteristics of regional distribution of national river run-off strength index(h c ), river run-off strength can be divided into three levels: weak, medium and strong. Using formula 4-3 to calculate, its value range is from 0.13 to 0.87, possibility of waterlogging which corresponds to these levels is in table 6 below. Table 6. Possibility of waterlogging corresponds to river run-off strength index table. Level of river run-off strength index Weak Medium Strong P 0.13~ ~ ~0.87 Possibility of water damage of highway along Rarely river occur May occur Easily occur Application of Water Damage of Highway in Mountains Areas Judgment Model Researchers choose 8 areas to pre-judge possibility of waterlogging, according to investigation and calculation of areas water damage factors, get the basic data as table 7 shown. Table 7. Basic data of areas water damage factors of highway in mountains areas table. Area Number of days which daily rainfall larger than 25 mm annual rainfall factor Plants coverage plants coverage Drainage density(m / km 2 ) drainage density Valley proportion valley proportion Xiaying Chuanfangg u ship Luozhuangzi Yuyang Guanzhuang Mashenqiao Bieshan ship Xilonghuxia 12d % % d % % d % % d % % d % % d % % d % % d % % 0.85 Put the above data into formula 4-3, we can get rivers and streams run-off strength of roads along river in mountains areas through calculation then judge possibility of water damage, make the preliminary judgment to time nodes and types of waterlogging, results are listed as follows: 80

4 Table 8. Possibility of areas where appear waterlogging in mountains areas pre-judge analyzation table. Highway area River run-off strength index Hc Possibility Xiaying Easily occur Chuanfanggu ship Luozhuangzi 0.57 May occur May occur Yuyang 0.75 Easily occur Guanzhuang May occur Mashenqiao May occur Bieshan ship May occur Xilonghuxia Easily occur Time node Possible water damage type Prevention scheme Reinforce bridge, culvert and subgarde culvert Soaking retaining wall Soaking retaining wall culvert, retaining wall Retaining wall Retaining wall culvert, retaining wall In order to verify accuracy of pre-judging result, researchers get statistical data about loss of water damage of highway along river in mountainous areas from 2011 to 2016 from relevant departments members in table 9 below: Table 9. Table of water damage loss situation of highway along river in mountains areas. Year Water damage item Area Loss situation Rectification situation Xiaying bridge of Xiaying Bridge was Meet the emergency first then Maying road Kuliyu submersible Xiaying Bridge was Meet the emergency first then bridge of Maku Road Longqian bridge of Xilonghuxi Bridge was Meet the emergency first then Longzhang Road a Guanxu bridge of Guanzhuan Bridge was Meet the emergency first then Guanxu Road g Xiluzhuang bridge Yuyang Bridge was Meet the emergency first then Bieshan bridge Bieshan Bridge was Meet the emergency first then Limutai submersible Xiaying Culvert was Meet the emergency first then culvert The above areas consistent with judgment result of pre-judging model, positive method indicates that model is scientific and effective to ensure high risk areas of water damage and then focus on. Comparative Analysis of Preventive Effect The work of prevention and controlling before disasters was carried out through application of waterlogging pre-judging and identification technique of highway lower slope in Jibei mountainous areas along river in 2015, then its hidden trouble factors were restrained and eradicated, also water damage disasters were under control. Comparing with situation without applying pre-judge technique in 2014, we can get the comparison chart below: 81

5 Subgrade collapse Soaking retaining wall damage Slope slump damage Figure 1. The contrast picture of spur-dike prevention adversities effect. Through the chart we can learn that waterlogging identification technique of highway along river in mountainous areas is effective to reduce loss caused by water logging and improve accuracy of prevention and controlling before disaster Conclusion Prevention and controlling work of waterlogging need researchers to improve the research on evaluation system, use efficient and scientific identification judgment technique to guide deployment of prevention and controlling work, accelerate level of preventing and reducing disaster of highway in mountains areas, drive economic development of mountains areas well at the safe and peaceful environment. References [1] Bao-cheng Ma, Wei-ping Tian, Li-xiao Fan, Research on risk identification of water damage disaster area of highway along river[j], Transportation Enterprise Management, 2014, 29(10): [2] Jie Zhong, Hong-yue Sun. Research on detecting factors of water damage of highway along river in mountains areas[j], East China Highway, 2011, (4): [3] Hua-wei Zhang. Analysis on waterlogging and preventing measures of highway along river in mountains areas[j], Science & Technology Vision, 2013, (6): [4] Wei-dong Feng. Brief talk about defensive technical measures of waterlogging of highway along river[j], Northeastern Highway, 2002, (4): [5] Cheng-gang Feng, Types of Water damage and defensive measures of slope of highway along river[j], Communications Standardization, 2014, 42(5),