Abstract:
Disclosed is a bank erosion protecting system having a roll mat wound in a roll type and embedded at a top portion of a bank so that when the bank slope starts collapsing, the roll mat may automatically cover the bank slope.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to Korean Patent Application No. 10-2013-0138146, filed on Nov. 14, 2013, and all the benefits accruing therefrom under 35 U.S.C. §119, the contents of which in its entirety are herein incorporated by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    The present disclosure relates to a bank erosion protecting system using an embedded roll mat, and more particularly, to a bank erosion protecting system having a roll mat wound in a roll type and embedded at a top portion of a bank so that the roll mat automatically covers the bank slope when the bank in the main channel is eroded and failed due to a bank erosion or bank failure. 
         [0004]    2. Description of the Related Art 
         [0005]    A river side below a bank formed at a river, channel or reservoir may be eroded due to a flood or typhoon (hurricane), which results in erosion of the bank. Generally, waterfront facilities such as trails, sport outfits, washrooms or the like are installed at the rear of the top of a bank. Therefore, if the bank is eroded, the waterfront facilities will be seriously damaged. 
         [0006]    In order to prevent bank erosion, concrete blocks may be installed at a bank slope, as disclosed in Korean Patent Registration No. 10-0477379. However, the install of such blocks at a bank slope is not suitable for protecting an ecologically stabilized bank. If an artificial structure such as blocks is installed at an ecologically stabilized bank slope, the bank slope becomes an inappropriate place for the growth of animals or plants. 
       SUMMARY 
       [0007]    The present disclosure is directed to providing a system for preventing an occurrence of abrupt bank erosion to ensure enough time to take an additional protective action to a bank. 
         [0008]    In addition, the present disclosure is directed to providing a system for minimizing ecological and environmental disturbance in the bank even though a facility for preventing bank erosion is installed at the bank slope. 
         [0009]    In one aspect of the present disclosure, there is provided a bank erosion protecting system, which includes: a roll mat having one end wound into a roll shape and embedded in the ground at a top of a bank, wherein one end of the roll mat wound into a roll shape is disposed toward a river and the other end of the roll mat is disposed at the back of the bank in an unrolled state; and riprap installed on the roll mat, wherein when a bank slope collapses, soil supporting the rolled portion of the roll mat is swept so that the rolled portion of the roll mat is unrolled and spread to cover the bank slope, and the riprap or stone also covers the roll mat spread over the bank slope, thereby preventing the bank slope from additionally collapsing. 
         [0010]    In the present disclosure, if a bank slope starts collapsing, a roll mat embedded in the bank starts unrolling to cover the bank slope, and subsequently riprap or stone contained in a trench flows down to the bank slope. Therefore, it is possible to efficiently preventing the bank slope from additionally collapsing. 
         [0011]    In addition, in the present disclosure, since the collapsing bank slope is covered by the roll mat and the riprap or stone, even though water swells to the bank slope, it is possible to effectively prevent soil of the bank slope from collapsing due to the water swelling or sediment winnowing. 
         [0012]    In particular, in the present disclosure, when a bank slope starts collapsing, the collapsing of the bank slope may be rapidly intercepted by means of the roll mat and the riprap or stone. Therefore, it is possible to permanently prevent bank erosion and also easily ensure enough time to stably protect the bank until an additional work for recovering a collapsed bank starts. 
         [0013]    In the present disclosure, it is just needed to excavate only a top portion of the bank (a floodplain). Therefore, even though the bank slope is already ecologically stabilized, it is possible to take a measure to prevent collapse of the bank slope in an easy and rapid way without disturbing ecologic environments. 
         [0014]    In the present disclosure, the roll mat may be wound and bound again into a roll shape not to be unrolled again, and after a collapsed bank slope is recovered, riprap or stone may be installed to be supported by the roll mat for preventing sediment winnowing through riprap. By doing so, the roll mat may be very usefully recycled. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a schematic perspective view showing a roll mat and riprap installed at a bank. 
           [0016]      FIG. 2  is a schematic cross-sectional view taken along the line A-A of  FIG. 1 . 
           [0017]      FIG. 3  is a schematic perspective view showing a trench formed at a top of a bank to install a roll mat and riprap or stone at the bank. 
           [0018]      FIG. 4  is a schematic cross-sectional view taken along the line B-B of  FIG. 3 . 
           [0019]      FIG. 5  is a schematic perspective view showing that a roll mat is disposed at the trench as depicted in  FIG. 1  after the state of  FIG. 3 . 
           [0020]      FIG. 6  is a schematic cross-sectional view taken along the line C-C of  FIG. 5 . 
           [0021]      FIG. 7  is a schematic cross-sectional view showing that a bank starts collapsing. 
           [0022]      FIG. 8  is a schematic cross-sectional view showing that the roll mat is unrolled after the state of  FIG. 7  to cover a collapsed bank slope. 
           [0023]      FIG. 9  is a schematic cross-sectional view showing that the riprap or stone collapses after the state of  FIG. 8  to cover the roll mat. 
           [0024]      FIG. 10  is a schematic cross-sectional view showing that a roll mat unrolled over the bank slope is wound and bound again into a roll state for recycling. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]      FIG. 1  is a schematic perspective view showing a roll mat and riprap installed at a bank according to the present disclosure.  FIG. 2  is a schematic cross-sectional view taken along the line A-A of  FIG. 1 . For reference, in the specification, the term “river” is used to have a meaning including artificial channels and reservoirs as well as natural rivers. 
         [0026]    In the present disclosure, a roll mat  10  is embedded in the ground at a top of a bank (a floodplain). One side of the roll mat  10  is wound into a roll shape, and the rolled portion of the roll mat  10  is disposed toward a river. When being wound into a roll shape, one side of the roll mat  10  is rolled so that its end is rolled upwards as shown in  FIGS. 1 and 2 , which is more advantageous in spreading the roll mat  10  over the bank slope when the bank collapses. 
         [0027]    In the embodiment depicted in  FIG. 2 , the other side of the roll mat  10  is unrolled toward the back of the bank, and riprap  20  is piled over the unrolled portion of the roll mat  10 , so that the roll mat  10  and the riprap  20  will be embedded together in the ground. 
         [0028]      FIG. 3  is a schematic perspective view showing a trench formed at a top of a bank to install the roll mat  10  and the riprap  20 .  FIG. 4  is a schematic cross-sectional view taken along the line B-B of  FIG. 3 . As shown in  FIGS. 3 and 4 , the top surface of the bank  100  is excavated to form a trench  110  at which the roll mat  10  is to be disposed. In the present disclosure, the bank is not entirely dug or damaged, but just the top surface of the bank is excavated to a certain depth to form the trench  110  while remaining the bank slope as it is. In particular, in the present disclosure, the trench  110  may be formed at the bank only in a region where bank erosion is expected. For example, in case of a river, based on a direction along which the river flows (or, a longitudinal direction), the trench  110  may be excavated at the top of the bank in the longitudinal direction only for a region where bank collapse is expected, as shown in  FIGS. 3 and 4 . 
         [0029]      FIG. 5  is a schematic perspective view showing that the roll mat  10  is disposed at the trench  110  as depicted in  FIG. 1 .  FIG. 6  is a schematic cross-sectional view taken along the line C-C of  FIG. 5 . As shown in  FIGS. 5 and 6 , after the trench  110  is completely formed, the roll mat  10  is disposed in the trench  110 . When the roll mat  10  is disposed in the trench  110 , the rolled portion of the roll mat  10  is located toward the river, and the other end of the roll mat  10  is unrolled into a flat state and located at the bottom of the trench  110 . 
         [0030]    After the roll mat  10  is disposed in the trench  110 , the riprap  20  is placed on the unrolled portion of the roll mat  10  in the trench  110  as shown in  FIGS. 1 and 2  and the trench  100  is filled with the riprap  20 . 
         [0031]      FIG. 7  is a schematic cross-sectional view showing that the bank slope has geometric changes by erosion or failure in the state of  FIG. 2 . As shown in  FIG. 7 , if a flood occurs, the bank slope has geometric changes by erosion or failure, and accordingly soil of the bank supporting the rolled portion of the roll mat  10  is swept.  FIG. 8  is a schematic cross-sectional view showing a state after the  FIG. 7 . If the soil supporting the roll mat  10  is swept, the rolled portion of the roll mat  10  is unrolled as shown in  FIG. 8 , and accordingly the roll mat  10  covers the bank slope. As the rolled portion of the roll mat  10  is unrolled, the unrolled portion of the roll mat  10  covers a swept surface of the bank slope. 
         [0032]    The riprap  20  placed on the roll mat  10  collapses onto the roll mat  10  to cover the roll mat  10  unrolled over the bank slope.  FIG. 9  is a schematic cross-sectional view showing that the riprap  20  covers the roll mat  10  unrolled over the bank slope after the state of  FIG. 8 . 
         [0033]    As described above, in the present disclosure, if the bank slope collapses, the rolled portion of the roll mat  10  is unrolled so that the roll mat  10  covers the bank slope, and along with it, the riprap  20  placed on the roll mat  10  also collapses onto the roll mat  10  to cover the roll mat  10 . In this way, the bank slope which is likely to additionally collapse is covered and protected by the roll mat  10  and the riprap  20 . Therefore, it is possible to efficiently prevent the bank slope from additionally collapsing. 
         [0034]    If a level of the river rises due to a flood or the like, water may swell to the bank slope from the inside of the bank. In the present disclosure, since the collapsing bank slope is covered by the roll mat  10  and the riprap  20 , even though water swells to the bank slope, it is possible to effectively prevent soil of the bank slope from being swept due to water swelling or sediment winnowing by water. 
         [0035]    In the present disclosure, when the bank slope starts collapsing, collapsing of the bank slope may be rapidly intercepted by means of the roll mat  10  and the riprap  20 . Therefore, it is possible to permanently prevent bank erosion and also easily ensure enough time to stably protect the bank until an additional work for recovering a collapsed bank starts. 
         [0036]    In particular, when the roll mat  10  and the riprap  20  are installed, it is just needed to excavate only a top surface of the bank. Therefore, even though the bank slope is already ecologically stabilized, it is possible to take a measure to prevent possible collapse of the bank slope in an easy and rapid way without disturbing ecologic environments. 
         [0037]      FIG. 10  is a schematic cross-sectional view showing that after the riprap  20  covering the roll mat  10  is removed, the roll mat  10  unrolled over the bank slope is wound and bound again into a roll state so as not to be unrolled again. In the present disclosure, the roll mat  10  may be wound and bound again into a roll shape not to be unrolled again, and after the collapsed bank slope is recovered, riprap  20  may be installed to be supported by the roll mat  10 . By doing so, the roll mat  10  may be very usefully recycled. 
         [0038]    The roll mat  10  may be made of natural fiber. In order to recover the bank slope, soil may be placed on the roll mat  10  and the riprap  20  spread over the bank slope. If the roll mat  10  is made of natural fiber, the roll mat  10  may be recycled as a material for survival and growth of plants at the recovered bank slope.